Aerosol-generating article with liquid-impervious wrapper, aerosol-generating system, and a method of using the aerosol-generating article

ABSTRACT

The aerosol-generating article include a plurality of elements coaxially aligned and assembled within a wrapper, the article having an outlet end and a distal end upstream from the outlet end. The article includes a liquid aerosol-forming substrate, and a liquid retention medium for retaining the liquid aerosol-forming substrate. The wrapper is formed from a sheet of liquid-impervious material, the liquid retention medium being in a first element of the plurality of elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to,international application no. PCT/EP2017/063061, filed on May 30, 2017,and further claims priority under 35 U.S.C. §119 to European PatentApplication No. 16172262.4, filed on May 31, 2016, European PatentApplication No. 16172265.7, filed on May 31, 2016, European PatentApplication No. 16172263.2, filed on May 31, 2016, and European PatentApplication No. 16172287.1, filed on May 31, 2016, the entire contentsof each of which is incorporated herein by reference in their entirety.

BACKGROUND Field

Example embodiments relate to a consumable aerosol-generating articlefor use with an aerosol-generating device, an aerosol-generating system,and a method of using the aerosol generating article. The aerosolgenerating article may include a liquid aerosol-forming substrate, aliquid retention medium, and a liquid-impervious wrapper.

Related Art

There are generally two main categories of heated aerosol-generatingsystems that may be used to produce an aerosol by heating, rather thanby burning an aerosol-forming substrate. One system, which may bedescribed as an e-cigarette system, typically may include a liquidaerosol-forming substrate contained within a cartridge of an atomiserunit. On operation, liquid may be conveyed from the cartridge by a wick,where it may be vaporized by a heating coil. A second system, which maybe described as a heated tobacco system, may involve the heating of asolid substrate including modifying tobacco to produce an aerosol.

SUMMARY

At least a first embodiment is directed toward an aerosol-generatingarticle.

In one embodiment, the aerosol-generating article includes, a pluralityof elements coaxially aligned and assembled within a wrapper, thearticle having an outlet end and a distal end upstream from the outletend; a liquid aerosol-forming substrate; and a liquid retention mediumfor retaining the liquid aerosol-forming substrate, wherein the wrapperis formed from a sheet of liquid-impervious material, the liquidretention medium being in a first element of the plurality of elements.

In one embodiment, the liquid aerosol-forming substrate is releasablycontained within a frangible capsule, the frangible capsule being nearthe liquid retention medium for retaining the liquid aerosol-formingsubstrate within the article after its release from the frangiblecapsule.

In one embodiment, the frangible capsule is in the liquid retentionmedium.

In one embodiment, the liquid retention medium is in the form of a tubehaving a lumen, and the frangible capsule is located within the lumen ofthe tube.

In one embodiment, the liquid retention medium includes an absorbentpolymeric material.

In one embodiment, the frangible capsule is configured to be ruptured byapplication of an external force.

In one embodiment, the frangible capsule is configured to be pierced bya piercing element.

In one embodiment, the aerosol-generating article further includes, acooling section located downstream from the liquid retention element,the cooling section being a second element of the plurality of elements.

In one embodiment, the liquid aerosol-forming substrate includes between10 weight percent and 25 weight percent water, an aerosol former, and atleast one flavorant.

In one embodiment, the aerosol-generating article further includes, amouthpiece filter located at the outlet end of the article, themouthpiece filter being a third element of the plurality of elements.

In one embodiment, the aerosol-generating article further includes, aplug located at the distal end of the article, the article beingconfigured to draw air into the article at or adjacent to the distalend, through the article, and out of the outlet end of the article if anegative pressure is applied at the outlet end.

In one embodiment, the wrapper is one of a sheet of polymeric material,a sheet of treated paper, and a sheet of metallic foil.

At least another example embodiment relates to an aerosol-generatingsystem.

In one embodiment, the aerosol-generating system includes, anaerosol-generating article, the aerosol-generating article including, aplurality of elements coaxially aligned and assembled within a wrapper,the article having an outlet end and a distal end upstream from theoutlet end, a liquid aerosol-forming substrate, and a liquid retentionmedium for retaining the liquid aerosol-forming substrate, the wrapperbeing formed from a sheet of liquid-impervious material, the liquidretention medium being in a first element of the plurality of elements;and an electrically-operated aerosol-generating device, theelectrically-operated aerosol-generating device including a heatingelement for heating the aerosol-forming substrate to form an aerosol.

At least another example embodiment relates to a method of using anaerosol generating article.

In one embodiment, the method uses an aerosol generating article, wherethe aerosol-generating article includes a plurality of elementscoaxially aligned and assembled within a wrapper, the article having anoutlet end and a distal end upstream from the outlet end, a liquidaerosol-forming substrate, and a liquid retention medium for retainingthe liquid aerosol-forming substrate, the wrapper being formed from asheet of liquid-impervious material, the liquid retention medium beingin a first element of the plurality of elements, the method including,coupling the heated aerosol-generating article to anelectrically-operated aerosol-generating device; activating a heatingelement of the electrically-operated aerosol-generating device; anddrawing air through the heated aerosol-generating article, the liquidaerosol-forming substrate being vaporized by heat energy supplied by theheating element and condensed to form an aerosol entrained in the air.

In one embodiment, the liquid aerosol-forming substrate is containedwithin a frangible capsule, the method further including the step of,releasing the liquid aerosol-forming substrate from the frangiblecapsule such that it is retained within the article by the liquidretention medium.

BRIEF DESCRIPTION OF THE DRAWINGS

Features described in relation to one example embodiment may equally beapplied to other example embodiments. Example embodiments will now bedescribed, with reference to the accompanying drawings.

FIG. 1 illustrates a schematic longitudinal cross-section of a heatdiffuser of an aerosol-generating system, in accordance with an exampleembodiment;

FIG. 2A illustrates a longitudinal cross-section of anaerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2B illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2C illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2D illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2E illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2F illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2G illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 2H illustrates a longitudinal cross-section of anotheraerosol-generating article that may be used with the heat diffuser ofFIG. 1, in accordance with an example embodiment;

FIG. 3 illustrates the heat diffuser of FIG. 1, and theaerosol-generating article of FIG. 2A, connected to anaerosol-generating device, in accordance with an example embodiment;

FIG. 4 illustrates a longitudinal cross-section of an aerosol-generatingarticle with a heat diffuser, in accordance with an example embodiment;

FIG. 5 illustrates an aerosol-generating article, during use, engagedwith an aerosol-generating device that includes external heatingelements, in accordance with an example embodiment;

FIG. 6 illustrates an aerosol-generating article, during use, engagedwith an aerosol-generating device that includes an internal heatingelement, in accordance with an example embodiment; and

FIG. 7 illustrates an aerosol-generating article, during use, engagedwith an aerosol-generating device that includes an internal heatingelement and a removably coupled heat diffuser, in accordance with anexample embodiment.

DETAILED DESCRIPTION

Example embodiments will become more readily understood by reference tothe following detailed description of the accompanying drawings. Exampleembodiments may, however, be embodied in many different forms and shouldnot be construed as being limited to the example embodiments set forthherein. Rather, these example embodiments are provided so that thisdisclosure will be thorough and complete. Like reference numerals referto like elements throughout the specification.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises,” “comprising,”“includes,” and/or “including,” when used in this specification, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings set forth herein.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Example embodiments are described herein with reference to cross-sectionillustrations that are schematic illustrations of idealized embodiments(and intermediate structures). As such, variations from the shapes ofthe illustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, these example embodimentsshould not be construed as limited to the particular shapes of regionsillustrated herein, but are to include deviations in shapes that result,for example, from manufacturing. For example, an implanted regionillustrated as a rectangle will, typically, have rounded or curvedfeatures and/or a gradient of implant concentration at its edges ratherthan a binary change from implanted to non-implanted region. Likewise, aburied region formed by implantation may result in some implantation inthe region between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of this disclosure.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and this specification and will not beinterpreted in an idealized or overly formal sense unless expressly sodefined herein.

Unless specifically stated otherwise, or as is apparent from thediscussion, terms such as “processing” or “computing” or “calculating”or “determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical, electronicquantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

In the following description, illustrative embodiments may be describedwith reference to acts and symbolic representations of operations (e.g.,in the form of flow charts, flow diagrams, data flow diagrams, structurediagrams, block diagrams, etc.) that may be implemented as programmodules or functional processes including routines, programs, objects,components, data structures, etc., that perform particular tasks orimplement particular abstract data types. The operations be implementedusing existing hardware in existing electronic systems, such as one ormore microprocessors, Central Processing Units (CPUs), digital signalprocessors (DSPs), application-specific-integrated-circuits (ASICs),SoCs, field programmable gate arrays (FPGAs), computers, or the like.

Further, one or more example embodiments may be (or include) hardware,firmware, hardware executing software, or any combination thereof. Suchhardware may include one or more microprocessors, CPUs, SoCs, DSPs,ASICs, FPGAs, computers, or the like, configured as special purposemachines to perform the functions described herein as well as any otherwell-known functions of these elements. In at least some cases, CPUs,SoCs, DSPs, ASICs and FPGAs may generally be referred to as processingcircuits, processors and/or microprocessors.

Although processes may be described with regard to sequentialoperations, many of the operations may be performed in parallel,concurrently or simultaneously. In addition, the order of the operationsmay be re-arranged. A process may be terminated when its operations arecompleted, but may also have additional steps not included in thefigure. A process may correspond to a method, function, procedure,subroutine, subprogram, etc. When a process corresponds to a function,its termination may correspond to a return of the function to thecalling function or the main function.

As disclosed herein, the term “storage medium”, “computer readablestorage medium” or “non-transitory computer readable storage medium,”may represent one or more devices for storing data, including read onlymemory (ROM), random access memory (RAM), magnetic RAM, core memory,magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other tangible machine readable mediums for storinginformation. The term “computer-readable medium” may include, but is notlimited to, portable or fixed storage devices, optical storage devices,and various other mediums capable of storing, containing or carryinginstruction(s) and/or data.

Furthermore, at least some portions of example embodiments may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine or computer readable medium such as a computer readable storagemedium. When implemented in software, processor(s), processingcircuit(s), or processing unit(s) may be programmed to perform thenecessary tasks, thereby being transformed into special purposeprocessor(s) or computer(s).

A code segment may represent a procedure, function, subprogram, program,routine, subroutine, module, software package, class, or any combinationof instructions, data structures or program statements. A code segmentmay be coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

General Methodology:

Of the two main categories of heated aerosol-generating system(highlighted above), the e-cigarette system may require direct heatingof the liquid substrate with a heating coil, which may risk overheatingof the liquid, particularly if the cartridge may be near empty.Additionally, a typical e-cigarette system may be used by multiple adultvapers, and therefore may come into contact with many externalcontaminants. This may provide a potential hygiene issue.

A heated tobacco system using a consumable article containing a solidaerosol-forming substrate may produce a sensorially more acceptableaerosol, and may not have the same hygiene problems associated withe-cigarettes. An adult vaper may however desire a wide variety offlavors that may be possible with a liquid-based heated e-cigarettesystem.

A type of aerosol-generating system is an electrically operatedaerosol-generating system. Handheld electrically operatedaerosol-generating systems typically include an aerosol-generatingdevice that has a battery, control electronics and an electric heaterfor heating an aerosol-generating article designed specifically for usewith the aerosol-generating device. The aerosol-generating articleincludes an aerosol-forming substrate, such as a tobacco rod or atobacco plug, and the heater that may be contained within theaerosol-generating device may be inserted into or around theaerosol-forming substrate when the aerosol-generating article may beinserted into the aerosol-generating device.

It may be difficult to evenly heat the aerosol-forming substrate withthe electric heater. This may lead to some areas of the aerosol-formingsubstrate being over-heated, and may lead to some areas of theaerosol-forming substrate being under-heated. Both may make it difficultto maintain consistent aerosol characteristics. This may be a particularissue with aerosol-generating articles in which the aerosol-formingsubstrate may be a liquid aerosol-forming substrate, since depletion ofthe aerosol-forming substrate may cause one or more parts of theaerosol-generating article to overheat. It therefore may be advantageousto provide means for mitigating the above described problems.

In at least one example embodiment there is provided an electricallyoperated aerosol-generating system comprising an aerosol-generatingarticle and an electrically operated aerosol-generating device. Theaerosol-generating article may include an aerosol-forming substrate,with an outlet end and a distal end upstream from the outlet end. Theelectrically operated aerosol-generating device may include a housinghaving a cavity configured to receive the distal end of theaerosol-generating article. The aerosol-generating system may furtherinclude an electric heating element and a heat diffuser including anon-combustible porous body for absorbing heat from the electric heatingelement such that, in use, air may be drawn through theaerosol-generating article from the distal end to the outlet end, andmay be heated by the heat absorbed in the porous body.

As used herein, the term “heated aerosol-generating article” may referto an article comprising an aerosol-generating substrate that, whenheated, may release volatile compounds that may form an aerosol. A“heated aerosol-generating article” refers to an article including anaerosol-forming substrate that is intended to be heated, rather thancombusted, in order to release volatile compounds that can form anaerosol. The aerosol formed by heating the aerosol-forming substrate maycontain fewer known harmful constituents than would be produced bycombustion or pyrolytic degradation of the aerosol-forming substrate. Inan embodiment, the aerosol-generating article is removably coupled to anaerosol-generating device. The article may be disposable or reusable.

As used herein, the term “aerosol-generating device” is a device thatengages or interacts with a heated aerosol-generating article to form anaerosol. The device that interacts with an aerosol-forming substrate maygenerate an aerosol. An electrically operated aerosol-generating devicemay be a device including one or more elements used to supply energyfrom a power supply (e.g., an electrical power supply), in order to heatan aerosol-forming substrate to generate an aerosol. Theaerosol-generating device may be an electrically operatedaerosol-generating device including a heating structure that is operatedby electrical power to heat an aerosol-forming substrate of anaerosol-generating article to generate an aerosol. The heating structuremay be a heater for heating air supplied to an aerosol-formingsubstrate. The heating structure may be an inductor for heating asusceptor, for example to heat air supplied to an aerosol-formingsubstrate.

An aerosol-generating device may be described as a heatedaerosol-generating device, which is an aerosol-generating deviceincluding a heating element. The heating element or heater may be usedto heat an aerosol-forming substrate of an aerosol-generating article togenerate an aerosol, or the solvent-evolving substrate of a cleaningconsumable to form a cleaning solvent. An aerosol-generating device maybe an electrically heated aerosol-generating device, which may be anaerosol-generating device including a heating element that may beoperated by electrical power to heat an aerosol-forming substrate of anaerosol-generating article to generate an aerosol.

The electric heating element may form part of the aerosol-generatingarticle, part of the heat diffuser, part of the aerosol-generatingdevice, or any combination thereof. In an embodiment, the electricheating element forms part of the device.

In an embodiment, the heat diffuser may form part of theaerosol-generating article or the aerosol-generating device. In anembodiment, the heat diffuser is removably coupled to theaerosol-generating device. In an embodiment, the heat diffuser may formpart of the aerosol-generating article, or may be an independent elementthat does not form part of the aerosol-generating article or theaerosol-generating device. The heat diffuser may be removably coupled tothe aerosol-generating article and the aerosol-generating device. Thedevice may be configured to removably coupled to the heat diffuser. Thecavity of the device may be configured to removably receive the heatdiffuser. The electric heating element may be configured to thermallycouple with the heat diffuser when the heat diffuser is removablycoupled to the aerosol-generating device. The electric heating elementmay be configured to thermally couple with the heat diffuser when theheat diffuser is received in the cavity of the aerosol-generatingdevice.

In this document, the term ‘removably coupled’ or ‘removably couplable’is used to mean that two or more elements of the system, such as theheat diffuser and the device, or the article and the device, may becoupled and uncoupled from one another without significantly damagingeither element. For example, the article may be removed from the devicewhen the aerosol-forming substrate has been consumed. The heat diffusermay be disposable. The heat diffuser may also be reusable.

The heat diffuser may be a removable element of the aerosol-generatingsystem. For example, the heat diffuser may be in the form of a removablycoupled and/or couplable element that engage with the aerosol generatingdevice to alter the manner in which the aerosol generating device heatsthe aerosol generating articles. For example, the aerosol generatingdevice may include an insertable heating element for insertion into asolid aerosol forming substrate of a heated aerosol-generating article.The heating element may contact the solid aerosol-forming substrate andheat it to generate an aerosol. The heat diffuser may be configured toengage with the insertable heating element. The heat diffuser may thenbe heated by the heating element, and the heated air may pass throughthe heating element. The heated air may volatilize an aerosol-formingsubstrate of a heated aerosol-generating article that may be locateddownstream of the heat diffuser. In this way, the manner in which theaerosol-generating device may heat an aerosol-forming substrate may bechanged from direct contact to an indirect heating of air. The sameaerosol-generating device may be used to heat different types ofaerosol-generating article, thereby providing a greater choice for theadult vaper.

In an embodiment, the system may be configured such that when the heatdiffuser is coupled to the aerosol-generating device, the heat diffuserabsorbs heat from the electric heating element, and air drawn throughthe aerosol-generating article from the distal end to the outlet end maybe heated by the heat absorbed in the porous body of the heat diffuser.The system may further be configured such that when the heat diffusermay not be coupled to the aerosol-generating device, theaerosol-generating article may absorb heat from the electric heatingelement.

Advantageously, in use, the heat diffuser may absorb heat from a heatingelement, and transfer the heat to air that may be drawn through the heatdiffuser so that the air may heat the aerosol-forming substratedownstream of the heat diffuser, primarily via a convection heatingprocess. This may provide more even heating of the aerosol-formingsubstrate, relative to systems in which the aerosol-forming substrate isheated primarily via a conduction heating process provided by theheating element. For example, areas of local high temperature, or “hotspots”, may be prevented from occurring in the aerosol-forming substratethat may otherwise be caused by conductive heating. This may be ofparticular benefit when the heat diffuser is used withaerosol-generating articles in which the aerosol-forming substrate is aliquid aerosol-forming substrate, as it may help to prevent overheatingthat may otherwise result from depletion of the aerosol-formingsubstrate. In particular, if the aerosol-forming substrate includes aliquid aerosol-forming substrate held in a liquid retention medium, theheat diffuser may help to reduce or prevent overheating of theaerosol-forming substrate or the liquid retention medium, even when theliquid retention medium is dry.

The heat diffuser may be arranged and configured to heat the air tobetween about 180 degrees Celsius and 250 degrees Celsius. In anembodiment, the heat diffuser heats the air to between about 200 degreesCelsius and 220 degrees Celsius.

In an embodiment, the system includes a heated aerosol-generatingdevice, at least one heated aerosol-generating article having a liquidaerosol-forming substrate, and at least one heated aerosol-formingsubstrate having a solid aerosol-forming substrate, for example anaerosol-forming substrate made from homogenized tobacco material. Thesystem may further include a removably couplable heat diffuser forengagement with the aerosol-generating device to change the manner inwhich the aerosol-generating device provides heat to the aerosol-formingsubstrate.

The term “porous” includes materials that may be inherently porous, aswell as substantially non-porous materials that may be made porousand/or permeable through the provision of a plurality of holes. Theporous body may be formed from a plug of a porous material, such as aceramic or metal foam, for example. Alternatively, the porous body maybe formed from a plurality of solid elements between which a pluralityof apertures are provided. For example, the porous body may include abundle of fibres, or a lattice of interconnected filaments. The porousmaterial may have pores of a sufficient size that may allow air to bedrawn through the porous body, through the pores. For example, the poresin the porous body may have an average transverse dimension of less thanabout 3.0 mm, or more preferably less than about 1.0 mm, or mostpreferably less than about 0.5 mm. Alternatively or in addition, thepores may have an average transverse dimension that may be greater thanabout 0.01 mm. For example, the pores may have an average transversedimension that may be between about 0.01 mm and about 3.0 mm, or morepreferably between about 0.01 mm and about 1.0 mm, or most preferablybetween about 0.01 mm and about 0.5 mm.

The term “pores” relates to regions of a porous article that are devoidof material. For example, a transverse area of porous body may includeportions of the material forming the body, and portions that may bevoids between the portions of material.

The average transverse dimension of the pores may be calculated bytaking the average of the smallest transverse dimension of each of thepores. The pore sizes may be substantially constant along the length ofthe porous body. Alternatively, the pore sizes may vary along the lengthof the porous body.

The term “transverse dimension” refers to a dimension that is in adirection which may be substantially perpendicular to the longitudinaldirection of the heated aerosol-generating article, the electricallyoperated aerosol-generating device, or the porous body.

The porosity distribution of the porous body may be substantiallyuniform. That is, the pores within the porous body may be distributedsubstantially evenly over the transverse area of the porous body. Theporosity distribution may differ across the transverse area of theporous body. That is, the local porosity in one or more sub-areas of thetransverse area may be greater than the local porosity in one or moreother sub-areas of the transverse area. For example, the local porosityin one or more sub-areas of the transverse area may be between 5 percentand 80 percent greater than the local porosity in one or more othersub-areas of the transverse area.

The term “transverse area” relates to an area of the porous body that isin a plane generally perpendicular to the longitudinal dimension of theporous body. For example, the porous body may be a rod and thetransverse area may be a cross-section of the rod taken at any lengthalong the rod, or the transverse area may be an end face of the rod.

The term “porosity” refers to the volume fraction of void space in aporous article. As used herein, the term “local porosity” refers to thefraction of pores within a sub-area of the porous body.

By varying the porosity distribution, air flow through the porous bodymay be altered as desired, for example to provide improved aerosolcharacteristics. For example, this porosity distribution may be variedaccording to the air flow characteristics of an aerosol-generatingsystem, or the temperature profile of a heating element, with which theheat diffuser is intended for use.

In an embodiment, the local porosity may be lower towards a centerportion of the porous body. With this arrangement, the air flow throughthe center portion of the porous body is decreased relative to theperiphery of the porous body. This may be advantageous depending on thetemperature profile of the heating element or on the airflowcharacteristics of the aerosol-generating system with which the heatdiffuser is intended for use. For example, this arrangement may be ofparticular benefit when used with an internal heating element positionedin use towards a central portion of the heat diffuser, since it mayallow for increased heat transfer from the heating element to the porousbody.

In an embodiment, the local porosity may be greater towards a centerportion of the porous body. This arrangement may enable increased airflow through the center of the porous body and may be advantageousdepending on the temperature profile of the heating element or on theairflow characteristics of the aerosol-generating system with which theheat diffuser is intended for use. For example, this arrangement may beof particular benefit when used with an external heating elementpositioned in use around the periphery of the heat diffuser, since itmay allow for increased heat transfer from the heating element to theporous body.

As porous bodies have a high surface-area-to-volume ratio, the heatdiffuser may allow quick and efficient heating of air drawn through theporous body. This may allow for homogenous heating of air drawn throughthe porous body and, consequently, more even heating of anaerosol-forming substrate downstream of the heat diffuser.

In an embodiment, the porous body has a surface area-to-volume ratio ofat least 20 to 1, or preferably at least 100 to 1, or more preferably atleast 500 to 1. Advantageously, this may provide a compact heat diffuserwhile allowing for particularly efficient transfer of thermal energyfrom the heating element to air drawn through the porous body. This maylead to faster, and more homogenous heating of air drawn through theporous body and, consequently, a more even heating of theaerosol-forming substrate downstream of the heat diffuser, relative toporous bodies having a lower surface area to volume ratios.

In an embodiment, the porous body has a high specific surface area. Thismay be a measure of the total surface area of a body per unit of mass.Advantageously, this may provide a low mass heat diffuser with a largesurface area for efficient transfer of thermal energy from the heatingelement to air drawn through the porous body. For example, the porousbody may have a specific surface area of at least 0.01 m² per gram, orpreferably at least 0.05 m² per gram, or more preferably at least 0.1 m²per gram, or most preferably at least 0.5 m² per gram.

The porous body may have an open cell porosity of between about 60percent to about 90 percent void volume to material volume.

In an embodiment, the porous body may have a low resistance to draw.That is, the porous body may offer a low resistance to the passage ofair through the heat diffuser. In such examples, the porous body may notsubstantially affect the resistance to draw of an aerosol-generatingsystem with which the heat diffuser is intended for use. In someembodiments, the resistance to draw (RTD) of the porous body may bebetween about 10 to 130 mm H₂O, or preferably between about 40 to 100 mmH₂O. The RTD of a specimen may refer to the static pressure differencebetween the two ends of the specimen when it may be traversed by an airflow under steady conditions in which the volumetric flow is 17.5millilitres per second at the output end. The RTD of a specimen may bemeasured using the method set out in ISO Standard 6565:2002 with anyventilation blocked.

The porous body may be formed from a heat storage material.

The term “heat storage material” refers to a material having a high heatcapacity. With this arrangement, the porous body may act as a heatreservoir, allowing the heat diffuser to absorb and store heat from theheating element and to subsequently release the heat over time to theaerosol-forming substrate, via air drawn through the porous body.

Where the porous body is formed from a heat storage material, the porousbody may be formed from a material having a specific heat capacity of atleast 0.5 J/g·K, or preferably at least 0.7 J/g·K, or more preferably atleast 0.8 J/g·K at 25 degrees Celsius and constant pressure. As thespecific heat capacity of a material may be effectively a measure of thematerial's ability to store thermal energy, forming the porous body froma material having a high heat capacity may allow the porous body toprovide a large heat reservoir for heating air drawn through the heatdiffuser without substantially increasing the weight of anaerosol-generating system with which the heat diffuser may be intendedfor use.

The porous body may be formed from any suitable material or materials.Where the porous body is formed from a heat storage material, suitablematerials may include, but may not limited to, glass fibre, glass mat,ceramic, silica, alumina, carbon, and minerals, or any combinationthereof.

The heat storage material may be thermally insulating. As used herein,the term “thermally insulating” refers to a material having a thermalconductivity of less than 100 W/m·K, or preferably less than 40 W/m·K,or less than 10 W/m·K at 23 degrees Celsius and a relative humidity of50%. This may result in a heat diffuser with a higher thermal inertia,relative to thermally conductive heat diffusers, in order to reducevariations in the temperature of air drawn through the porous body thatmay be caused by temperature fluctuations in the heating element. Thismay result in more consistent aerosol characteristics.

The porous body may be thermally conductive. As used herein, the term“thermally conductive” refers to a material having a thermalconductivity of at least 10 W/m·K, or preferably at least 40 W/m·K, ormore preferably at least 100 W/m·K at 23 degrees Celsius and a relativehumidity of 50%. Where the porous body is thermally conductive, theporous body may be formed from a material having a thermal conductivityof at least 40 W/m·K, or preferably at least 100 W/m·K, or morepreferably at least 150 W/m·K, or most preferably at least 200 W/m·K at23 degrees Celsius and a relative humidity of 50%.

Advantageously, this may reduce the thermal inertia of the heat diffuserand allow the temperature of the heat diffuser to quickly adjust tochanges in the temperature of the heating element, for example where theheating element may be heated according to a heating regime which maychanges over time, while still allowing the air drawn through the porousbody to be evenly heated. Further, by having a high thermalconductivity, the thermal resistance through the porous body may belower. This may allow the temperature of portions of the porous bodywhich may be remote from the heating element in use to be at a similarlyhigh temperature as the portions of the porous body which are closest tothe heating element in use. This may provide for particularly efficientheating of air drawn through the porous body.

Where the porous body is thermally conductive, the porous body may beformed from a material having a thermal conductivity of at least 40W/m·K, or preferably at least 100 W/m·K, or more preferably at least 150W/m·K, or most preferably at least 200 W/m·K at 23 degrees Celsius and arelative humidity of 50%.

Where the porous body is thermally conductive, suitable thermallyconductive materials may include, but are not limited to, aluminium,copper, zinc, steel, silver, thermally conductive polymers, or anycombination or alloy thereof.

In an embodiment, the porous body is formed from a heat storage materialwhich is also thermally conductive, such as aluminium.

In an embodiment in which the heat diffuser does not form part of theaerosol-generating device, the porous body may be configured to bepenetrated by an electric heating element forming part of anaerosol-generating device when the heat diffuser is coupled to theaerosol-generating device. The term “penetrated” is used to mean thatthe heating element at least partially extends into the porous body.Thus, the heating element may be sheathed within the porous body. Withthis arrangement, by the act of penetration, the heating element may bebrought into close proximity to, or contact with, the porous body. Thismay increase heat transfer between the heating element and the porousbody and, consequently, to air drawn through the porous body relative toexamples in which the porous body may not be penetrated by the heatingelement.

The heating element may conveniently be shaped as a needle, pin, rod, orblade that may be inserted into the heat diffuser. Theaerosol-generating device may comprise more than one heating element,and in this document a heating element mean one or more heatingelements.

The porous body may define a cavity or hole for receiving the electricheating element when the heat diffuser may be coupled to theaerosol-generating device.

In an embodiment, the porous body may be rigid.

The porous body may be pierceable by the heating element when the heatdiffuser is coupled to the aerosol-generating device. For example, theporous body may comprise a foam, such as a polymer, metal or ceramicfoam, that is pierceable by the heating element.

In an embodiment, the electric heating element may be provided as partof an aerosol-generating device with which the heat diffuser is intendedfor use, or as part of the aerosol-generating article with which theheat diffuser is intended for use, as part of the heat diffuser, or anycombination thereof. The electric heating element may be coupled to theporous body of the heat diffuser. The heat diffuser may comprise anelectric heating element thermally coupled to the porous body. In suchembodiments, the porous body is arranged to absorb heat from the heatingelement and transfer it to air drawn through the porous body. With thisarrangement, the heating element may be easily replaced by replacing theheat diffuser, while allowing the aerosol-generating device to be reusedwith a new heat diffuser.

The electric heating element may include one or more external heatingelements, one or more internal heating elements, or one or more externalheating elements, and one or more internal heating elements. As usedherein, the term “external heating element” refers to a heating elementthat is positioned outside of the heat diffuser when anaerosol-generating system including the heat diffuser is assembled. Asused herein, the term “internal heating element” refers to a heatingelement that is positioned at least partially within the heat diffuser,when an aerosol-generating system including the heat diffuser isassembled. The electric heating element may be embedded in the porousbody of the heat diffuser.

The one or more external heating elements may include an array ofexternal heating elements that may be arranged around the periphery ofthe heat diffuser, for example on the outer surface of the porous body.In certain examples, the external heating elements may extend along thelongitudinal direction of the heat diffuser. With this arrangement, theheating elements may extend along the same direction in which the heatdiffuser may be inserted into and removed from a cavity in anaerosol-generating device. This may reduce interference between theheating elements and the aerosol-generating device relative to devicesin which the heating elements may not be aligned with the length of theheat diffuser. In an embodiment, the external heating elements mayextend along the length direction of the heat diffuser and may be spacedapart in the circumferential direction. Where the heating elementincludes one or more internal heating elements, the one or more internalheating elements may include any suitable number of heating elements.For example, the heating element may include a single internal heatingelement. The single internal heating element may extend along thelongitudinal direction of the heat diffuser.

Where the electric heating element forms part of the heat diffuser, theheat diffuser may further include one or more electrical contacts bywhich the electric heating element may be connectable to a power supply,for example a power supply in the aerosol-generating device.

The electric heating element may be an electrically resistive heatingelement.

The electric heating element may include a susceptor in thermal contactwith the porous body. The electric heating element may be a susceptorforming part of the heat diffuser. In an embodiment, the susceptor maybe embedded in the porous body.

The term ‘susceptor’ refers to a material that can convertelectromagnetic energy into heat. When located within a fluctuatingelectromagnetic field, eddy currents induced in the susceptor may causeheating of the susceptor. As the susceptor is in thermal contact withthe heat diffuser, the heat diffuser may be heated by the susceptor.

In such embodiments, the heat diffuser may be designed to engage with anelectrically-operated aerosol-generating device including an inductionheating source. The induction heating source, or inductor, may generatethe fluctuating electromagnetic field for heating a susceptor locatedwithin the fluctuating electromagnetic field. In use, the heat diffusermay engage with the aerosol-generating device such that the susceptormay be located within the fluctuating electromagnetic field generated bythe inductor.

The susceptor may be in the form of a pin, rod, or blade. The susceptormay have a length of between 5 mm and 15 mm, or for example between 6 mmand 12 mm, or between 8 mm and 10 mm. The susceptor may have a width ofbetween 1 mm and 5 mm and may have a thickness of between 0.01 mm and 2mm, or for example between 0.5 mm and 2 mm. In an embodiment, thesusceptor may have a thickness of between 10 micrometres and 500micrometres, or more preferably between 10 and 100 micrometres. If thesusceptor has a constant cross-section, for example a circularcross-section, it may have a width or diameter of between 1 mm and 5 mm.

The susceptor may be formed from any material that can be inductivelyheated to a temperature sufficient to generate an aerosol from theaerosol-forming substrate downstream of the heat diffuser. Susceptorsmay include a metal or carbon. In an embodiment, a susceptor may includea ferromagnetic material, for example ferritic iron, or a ferromagneticsteel, or stainless steel. A suitable susceptor may be, or include,aluminium. Susceptors may be formed from 400 series stainless steels,for example grade 410, or grade 420, or grade 430 stainless steel.Different materials may dissipate different amounts of energy whenpositioned within electromagnetic fields having similar values offrequency and field strength. Thus, parameters of the susceptor such asmaterial type, length, width, and thickness may all be altered toprovide a desired power dissipation within a known electromagneticfield.

Susceptors may be heated to a temperature in excess of 250 degreesCentigrade. Suitable susceptors may include a non-metallic core with ametal layer disposed on the non-metallic core, for example metallictracks formed on a surface of a ceramic core.

A susceptor may have a protective external layer, for example aprotective ceramic layer or protective glass layer encapsulating thesusceptor. The susceptor may include a protective coating formed by aglass, a ceramic, or an inert metal, formed over a core of thesusceptor.

The heat diffuser may contain a single susceptor. Alternatively, theheat diffuser may include more than one susceptor.

Heat diffusers may include a piercing member at one end of the porousbody. This may allow the heat diffuser to conveniently and easily piercea seal at an end of an aerosol-generating article with which it isintended for use when the heat diffuser is engaged with theaerosol-generating article. Where the aerosol-generating article withwhich the heat diffuser may include a frangible capsule, for example afrangible capsule containing an aerosol-forming substrate, the piercingmember may allow the heat diffuser to conveniently and easily pierce thefrangible capsule when the heat diffuser is engaged with theaerosol-generating article.

The downstream end of the piercing member may have a cross-sectionalarea that may be smaller than the cross-sectional area of the region ofthe piercing member immediately upstream of the downstream end. In anembodiment, the cross-sectional area of the piercing member may narrowtowards a tapered tip at its downstream end.

The piercing member may be formed by the porous body. Alternatively, thepiercing member may be a separate element attached at the downstream endof the porous body.

The aerosol-forming substrate may be a solid aerosol-forming substrate.Alternatively, the aerosol-forming substrate may include both solid andliquid elements. The aerosol-forming substrate may include tobacco. Theaerosol-forming substrate may include a tobacco-containing materialcontaining volatile tobacco flavor compounds which may be released fromthe substrate upon heating. The aerosol-forming substrate may include anon-tobacco material. The aerosol-forming substrate may include atobacco-containing material and a non-tobacco containing material.

The aerosol-forming substrate may further include an aerosol former thatmay facilitate the formation of a dense and stable aerosol. Examples ofsuitable aerosol formers may include glycerine and propylene glycol.

The aerosol-forming substrate may include a solid aerosol-formingsubstrate. The aerosol-forming substrate may include atobacco-containing material containing volatile tobacco flavor compoundswhich may be released from the substrate upon heating. Theaerosol-forming substrate may include a non-tobacco material.

The aerosol-forming substrate may include at least one aerosol former.As used herein, the term ‘aerosol former’ is used to describe anysuitable known compound or mixture of compounds that, in use,facilitates formation of an aerosol. Suitable aerosol formers aresubstantially resistant to thermal degradation at the operatingtemperature of the aerosol-generating article. Examples of suitableaerosol formers are glycerine and propylene glycol. Suitable aerosolformers may include, but may not be limited to: polyhydric alcohols,such as propylene glycol, triethylene glycol, 1,3-butanediol andglycerine; esters of polyhydric alcohols, such as glycerol mono-, di- ortriacetate; and aliphatic esters of mono-, di- or polycarboxylic acids,such as dimethyl dodecanedioate and dimethyl tetradecanedioate. In anembodiment, aerosol formers are polyhydric alcohols or mixtures thereof,such as propylene glycol, triethylene glycol, 1,3-butanediol andglycerine. The aerosol-forming substrate may include a single aerosolformer. Alternatively, the aerosol-forming substrate may include acombination of two or more aerosol formers. The aerosol-formingsubstrate may have an aerosol former content of greater than 5 percenton a dry weight basis. The aerosol-forming substrate may have an aerosolformer content of between approximately 5 percent and approximately 30percent on a dry weight basis. The aerosol-forming substrate may have anaerosol former content of approximately 20 percent on a dry weightbasis.

The aerosol-forming substrate may include a liquid aerosol-formingsubstrate. The liquid aerosol-forming substrate may include a nicotinesolution. The liquid aerosol-forming substrate may include atobacco-containing material including volatile tobacco flavor compounds,which are released from the liquid upon heating. The liquidaerosol-forming substrate may include a non-tobacco material. The liquidaerosol-forming substrate may include water, solvents, ethanol, plantextracts and natural or artificial flavors. The liquid aerosol-formingsubstrate may further include an aerosol former.

In an embodiment, the aerosol-generating article may include a liquidaerosol-forming substrate and a liquid retention medium for retainingthe liquid aerosol-forming substrate.

The liquid retention medium may include an absorbent material, forexample an absorbent polymeric material. Examples of suitable liquidretention materials may include fibrous polymers and porous polymers,such as open-cell foams. The liquid retention medium may include afibrous cellulose acetate or a fibrous cellulose polymer. The liquidretention medium may include a porous polypropylene material. Otherwell-known suitable materials capable of retaining a liquid may be used.

The liquid retention medium may either be located within an air-flowpath through the heated aerosol-generating article, or may define atleast a portion of an air-flow path through the aerosol-generatingarticle. In an embodiment, one or more holes defined through the liquidretention medium may define a portion of the air-flow path through theheated aerosol-generating article between the distal end of the articleand the outlet end of the article.

The liquid retention medium may be in the form of a tube having acentral lumen. Walls of the tube may be formed from, or include, asuitable liquid-retention material.

The liquid aerosol-forming substrate may be incorporated into the liquidretention medium immediately prior to use. For example, a dose of liquidaerosol-forming substrate may be injected into the liquid retentionmedium immediately prior to use.

Articles according to the invention may include a liquid aerosol-formingsubstrate contained within a frangible capsule. The frangible capsule isdescribed in greater detail below. In an embodiment, the aerosol-formingsubstrate is a liquid aerosol-forming substrate, and the article mayfurther include a frangible capsule containing the liquidaerosol-forming substrate, and a liquid retention medium downstream ofthe heat diffuser may be arranged to absorb the liquid aerosol-formingsubstrate when the frangible capsule may be broken.

The frangible capsule may be located within the porous carrier material.For example, the porous carrier material may be provided in the form ofa liquid retention tube and the frangible capsule may be located withinthe lumen of the tube.

The frangible capsule may be located adjacent to the liquid retentionmedium within the article such that the liquid-aerosol-forming substratemay be released from the frangible capsule and may contact and beretained by the liquid retention medium. The frangible capsule may belocated within the liquid retention medium. For example, the liquidretention medium may include a plug of material in which the capsule maybe embedded. In an embodiment, an article including a tubular liquidretention medium, and the frangible capsule containing the liquidaerosol-forming substrate, may be located within the lumen of thetubular liquid retention medium.

Where the aerosol-forming substrate is a solid aerosol-formingsubstrate, the solid aerosol-forming substrate may be immediatelydownstream of the heat diffuser. For example, the solid aerosol-formingsubstrate may abut the heat diffuser. In an embodiment, the solidaerosol-forming substrate may be spaced apart in the longitudinaldirection from the heat diffuser.

In an embodiment, the aerosol-forming substrate may be a liquidaerosol-forming substrate, and the article may further include a liquidretention medium for retaining the liquid aerosol-forming substrate. Inan embodiment, the liquid retention medium may be immediately downstreamof the heat diffuser. For example, the liquid retention medium may abutthe heat diffuser. In an embodiment, the liquid retention medium may bespaced apart in the longitudinal direction from the heat diffuser.

In an embodiment, the aerosol-forming substrate may be a liquidaerosol-forming substrate, and the article further may include a liquidretention medium for retaining the liquid aerosol-forming substrate,where the liquid retention medium may be spaced apart in thelongitudinal direction from the heat diffuser.

With this arrangement, conductive heat transfer between the heatdiffuser and the liquid retention medium, or a solid aerosol-formingsubstrate, may be reduced. This may further reduce or prevent areas oflocal high temperature, or “hot spots”, from occurring in the liquidretention medium, or the aerosol-forming substrate, that may otherwisebe caused by conductive heating.

Aerosol-generating articles may further include a support element thatmay be located immediately downstream of the aerosol-forming substrateor, where the article include a liquid retention medium for retaining aliquid aerosol-forming substrate, immediately downstream of the liquidretention medium. The support element may abut the aerosol-formingsubstrate or the liquid retention medium.

The support element may be formed from any suitable material, orcombination of materials. For example, the support element may be formedfrom one or more materials selected from the group consisting of:cellulose acetate; cardboard; crimped paper, such as crimped heatresistant paper or crimped parchment paper; and polymeric materials,such as low density polyethylene (LDPE). In an embodiment, the supportelement may be formed from cellulose acetate. The support element mayinclude a hollow tubular element. For example, the support element mayinclude a hollow cellulose acetate tube. The support element may have anexternal diameter that may be approximately equal to the externaldiameter of the aerosol-generating article.

The support element may have an external diameter of betweenapproximately 5 millimetres and approximately 12 millimetres, or forexample of between approximately 5 millimetres and approximately 10millimetres, or between approximately 6 millimetres and approximately 8millimetres. For example, the support element may have an externaldiameter of 7.2 millimetres+/−10 percent.

The support element may have a length of between approximately 5millimetres and approximately 15 mm. In an embodiment, the supportelement may have a length of approximately 8 millimetres.

An aerosol-cooling element may be located downstream of theaerosol-forming substrate. For example, an aerosol-cooling element maybe located immediately downstream of a support element, and may abut thesupport element. The aerosol-cooling element may be located immediatelydownstream of the aerosol-forming substrate or, where the articleincludes a liquid retention medium for retaining a liquidaerosol-forming substrate, immediately downstream of the liquidretention medium. For example, the aerosol-cooling element may abut theaerosol-forming substrate or the liquid retention medium.

The aerosol-cooling element may have a total surface area of betweenapproximately 300 square millimetres per millimetre length andapproximately 1000 square millimetres per millimetre length. In anembodiment, the aerosol-cooling element may have a total surface area ofapproximately 500 square millimetres per millimetre length.

The aerosol-cooling element may have a low resistance to draw. That is,the aerosol-cooling element may offer a low resistance to the passage ofair through the aerosol-generating article. In an embodiment, theaerosol-cooling element may not substantially affect the resistance todraw of the aerosol-generating article.

The aerosol-cooling element may include a plurality of longitudinallyextending channels. The plurality of longitudinally extending channelsmay be defined by a sheet material that may have been one or more ofcrimped, pleated, gathered and folded to form the channels. Theplurality of longitudinally extending channels may be defined by asingle sheet that may have been one or more of crimped, pleated,gathered and folded to form multiple channels. Alternatively, theplurality of longitudinally extending channels may be defined bymultiple sheets that may have been one or more of crimped, pleated,gathered and folded to form multiple channels.

In an embodiment, the aerosol-cooling element may include a gatheredsheet of material selected from the group consisting of metallic foil,polymeric material, and substantially non-porous paper or cardboard. Inan embodiment, the aerosol-cooling element may include a gathered sheetof material selected from the group consisting of polyethylene (PE),polypropylene (PP), polyvinylchloride (PVC), polyethylene terephthalate(PET), polylactic acid (PLA), cellulose acetate (CA), and aluminiumfoil.

In an embodiment, the aerosol-cooling element includes a gathered sheetof biodegradable material. For example, a gathered sheet of non-porouspaper or a gathered sheet of biodegradable polymeric material, such aspolylactic acid or any well-known commercially available family ofstarch based copolyesters. In an embodiment, the aerosol-cooling elementincludes a gathered sheet of polylactic acid.

The aerosol-cooling element may be formed from a gathered sheet ofmaterial having a specific surface area of between approximately 10square millimetres per milligram and approximately 100 squaremillimetres per milligram weight. In an embodiment, the aerosol-coolingelement may be formed from a gathered sheet of material having aspecific surface area of approximately 35 mm²/mg.

In use, the aerosol-cooling element may be arranged and configured tocool the heated air and vapor drawn through the element to between about80 degrees Celsius and 120 degrees Celsius. In an embodiment, theaerosol-cooling element cools the heated air and vapor drawn through theelement to about 100 degrees Celsius.

The aerosol-generating article may include a mouthpiece located at theoutlet end of the aerosol-generating article. The mouthpiece may belocated immediately downstream of an aerosol-cooling element, and mayabut the aerosol-cooling element. The mouthpiece may be locatedimmediately downstream of the aerosol-forming substrate or, where thearticle includes a liquid retention medium for retaining a liquidaerosol-forming substrate, immediately downstream of the liquidretention medium. In an embodiment, the mouthpiece may abut theaerosol-forming substrate, or the liquid retention medium. Themouthpiece may include a filter. The filter may be formed from one ormore suitable filtration materials. The filtration materials may be anywell-known material used for filtration purposes. In an embodiment, themouthpiece may include a filter formed from cellulose acetate tow.

The mouthpiece may have an external diameter that may be approximatelyequal to the external diameter of the aerosol-generating article. Themouthpiece may have an external diameter between approximately 5millimetres and approximately 10 millimetres, or between approximately 6millimetres and approximately 8 millimetres. In an embodiment, themouthpiece may have an external diameter of 7.2 millimetres+/−10%.

The mouthpiece may have a length of between approximately 5 millimetresand approximately 20 millimetres. For example, the mouthpiece may have alength of from about 7 mm to about 12 mm.

The elements of the aerosol-forming article may be circumscribed by anouter wrapper, for example in the form of a rod. The wrapper maycircumscribe at least a downstream portion of the heat diffuser. In anembodiment, the wrapper may circumscribe the heat diffuser alongsubstantially the entire length of the heat diffuser. The outer wrappermay be formed from any suitable material or combination of materials.The outer wrapper may be non-porous. The outer wrapper may beliquid-impervious.

The aerosol-generating article may be substantially cylindrical inshape. The aerosol-generating article may be substantially elongate. Theaerosol-generating article may have a length and a circumferencesubstantially perpendicular to the length. The aerosol-forming substrateor a porous carrier material in which the aerosol-forming substrate maybe absorbed during use, may be substantially cylindrical in shape. Theaerosol-forming substrate or the porous carrier material may besubstantially elongate. The aerosol-forming substrate, or the porouscarrier material, may also have a length and a circumferencesubstantially perpendicular to the length.

The aerosol-forming substrate or, where applicable, the liquid retentionmedium, may have a length of between about 7 mm and about 15 mm. In anembodiment, the aerosol-forming substrate, or the liquid retentionmedium, may have a length of approximately 10 mm. Alternatively, theaerosol-forming substrate, or the liquid retention medium, may have alength of approximately 12 mm.

The aerosol-generating substrate or liquid retention medium, may have anexternal diameter that may be approximately equal to the externaldiameter of the aerosol-generating article. The external diameter of theaerosol-forming substrate, or the liquid retention medium, may bebetween approximately 5 mm and approximately 12 mm. In an embodiment,the aerosol-forming substrate, or the liquid retention medium, may havean external diameter of approximately 7.2 mm+/−10 percent.

A heated aerosol-generating system may include an aerosol-generatingdevice and a heated aerosol-generating article that may include anycombination of the aerosol-generating devices and a heatedaerosol-generating articles described herein. The aerosol-generatingdevice may be an electrically operated aerosol-generating device.

An aerosol-generating device may be a heated aerosol-generating device,which may be an aerosol-generating device including a heating element orheater. The heating element or heater may be used to heat anaerosol-forming substrate of an aerosol-generating article to generatean aerosol.

The aerosol-generating device may be an electrically heatedaerosol-generating device, which may be an aerosol-generating deviceincluding a heating element that may be operated by electrical power toheat an aerosol-forming substrate of an aerosol-generating article togenerate an aerosol.

The aerosol-generating device may include electric circuitry configuredto control the supply of power from a power supply to an electricheating element of the system.

The aerosol-generating device of the aerosol-generating system mayinclude: a housing having a cavity for receiving the heatedaerosol-generating article and a controller configured to control thesupply of power from a power supply to an electric heating element ofthe system.

The electric heating element may include one or more heating elements.

In an embodiment, the electrically operated aerosol-generating devicemay include an electric heating element and a housing having a cavity,and wherein the heated aerosol-generating article may be received in thecavity. The heating element may conveniently be shaped as a needle, pin,rod, or blade that may be inserted into the article.

Aerosol-generating systems may include an electric heating element. Theelectric heating element may include one or more external heatingelements, one or more internal heating elements, or one or more externalheating elements and one or more internal heating elements. As usedherein, the term “external heating element” may refer to a heatingelement that may be positioned outside of the heat diffuser when anaerosol-generating system including the heat diffuser may be assembled.As used herein, the term “internal heating element” refer to a heatingelement that may be positioned at least partially within the heatdiffuser when an aerosol-generating system including the heat diffusermay be assembled.

The one or more external heating elements may include an array ofexternal heating elements arranged around the inner surface of thecavity. In an embodiment, the external heating elements may extend alongthe longitudinal direction of the cavity. With this arrangement, theheating elements may extend along the same direction in which the heatdiffuser and the article may be inserted into and removed from thecavity. This may reduce interference between the heating elements andthe heat diffuser relative to devices in which the heating elements maynot be aligned with the length of the cavity. In an embodiment, theexternal heating elements may extend along the length direction of thecavity and may be spaced apart in the circumferential direction. Wherethe heating element includes one or more internal heating elements, theone or more internal heating elements may include any suitable number ofheating elements. For example, the heating element may include a singleinternal heating element. The single internal heating element may extendalong the longitudinal direction of the cavity.

The electric heating element may include an electrically resistivematerial. Suitable electrically resistive materials may include, but arenot limited to: semiconductors such as doped ceramics, electrically“conductive” ceramics (such as, for example, molybdenum disilicide),carbon, graphite, metals, metal alloys and composite materials made of aceramic material and a metallic material. Such composite materials mayinclude doped or undoped ceramics. Examples of suitable doped ceramicsinclude doped silicon carbides. Examples of suitable metals includetitanium, zirconium, tantalum and metals from the platinum group.Examples of suitable metal alloys may include stainless steel, copper,nickel, cobalt, chromium, aluminium, titanium, zirconium, hafnium,niobium, molybdenum, tantalum, tungsten, tin, gallium, manganese, andiron-containing alloys, and super-alloys based on nickel, iron, cobalt,stainless steel, iron-aluminium based alloys andiron-manganese-aluminium based alloys. In composite materials, theelectrically resistive material may optionally be embedded in,encapsulated or coated with an insulating material or vice-versa,depending on the kinetics of energy transfer and the externalphysicochemical properties required. The heating element may include ametallic etched foil insulated between two layers of an inert material.In that case, the inert material may include commercially availablepolyimide films, all-polyimide or mica foil.

Where the electric heating element includes a susceptor in thermalcontact with the porous body of the heat diffuser, theaerosol-generating device may include an inductor arranged to generate afluctuating electromagnetic field within the cavity and an electricalpower supply connected to the inductor. The inductor may include one ormore coils that may generate a fluctuating electromagnetic field. Thecoil or coils may surround the cavity.

The device may be capable of generating a fluctuating electromagneticfield of between 1 and 30 MHz, for example, between 2 and 10 MHz, forexample between 5 and 7 MHz. In an embodiment, the device may be capableof generating a fluctuating electromagnetic field having a fieldstrength (H-field) of between 1 and 5 kA/m, for example between 2 and 3kA/m, for example about 2.5 kA/m.

In an embodiment, the aerosol-generating device may be a portable orhandheld aerosol-generating device.

The aerosol-generating device may be substantially cylindrical in shape

The aerosol-generating device may have a length of between approximately70 millimetres and approximately 120 millimetres.

The device may include a power supply for supplying electrical power tothe electric heating element. The power supply may be any suitable powersupply, for example a DC voltage source such as a battery. In oneembodiment, the power supply may be a Lithium-ion battery.Alternatively, the power supply may be a Nickel-metal hydride battery, aNickel cadmium battery, or a Lithium based battery, for example aLithium-Cobalt, a Lithium-Iron-Phosphate, Lithium Titanate or aLithium-Polymer battery.

The device may include electric circuitry for controlling the supply ofpower from the power supply to the electric heating element. Theelectric circuitry may include one or more microprocessors ormicrocontrollers.

As used herein, the terms ‘upstream’ and ‘downstream’ may be used todescribe the relative positions of elements, or portions of elements, ofthe heat diffuser, aerosol-generating article, or aerosol-generatingdevice, in relation to the direction in which air may be drawn throughthe system during use thereof.

As used herein, the term ‘longitudinal’ may be used to describe thedirection between the upstream end and the downstream end of the heatdiffuser, aerosol-generating article, or aerosol-generating device andthe term ‘transverse’ may be used to describe the directionperpendicular to the longitudinal direction.

As used herein, the term ‘diameter’ may be used to describe the maximumdimension in the transverse direction of the heat diffuser,aerosol-generating article, or aerosol-generating device. As usedherein, the term ‘length’ may be used to describe the maximum dimensionin the longitudinal direction.

An aerosol-generating article may be used together with anaerosol-generating device described above, or with an aerosol generatingdevice according to another embodiment. The aerosol-generating articlemay also be used with other aerosol generating devices (not described inthis document).

The heated aerosol-generating article may be referred to herein as anarticle. In one embodiment, the article may include a plurality ofelements which may be coaxially aligned and assembled within a wrapper.The article may have an outlet end and a distal end upstream from theoutlet end. The article may include a liquid aerosol-forming substrateand a liquid retention medium for retaining the liquid aerosol-formingsubstrate. The wrapper may be formed from a sheet of liquid-imperviousmaterial.

In an embodiment, a heated aerosol-generating article may use a solidaerosol-forming substrate that may be formed in the shape of a rod. Thewrapper that may be used to assemble or circumscribe the elements ofsuch articles may be a traditional porous cigarette paper. The use of aliquid aerosol-forming substrate may provide certain benefits over theuse of a solid aerosol-forming substrate. One such benefit is thegreater variety of flavors that may be provided in liquid substrateformulations, as compared to solid substrate formulations. Anotherbenefit may be the lower environmental odour associated with thevaporization of liquid substrates. However, it is desirable to provide aliquid aerosol-forming substrate in a consumable design that may have acigarette look and feel. The use of an article that has a plurality ofelements may include a liquid retention medium for retaining a liquidaerosol-forming substrate, and which may be assembled within aliquid-impervious wrapper to provide an advantage of an e-cigarette typesystem with the look, feel, and convenience of a heated tobacco system.

In an embodiment, the wrapper may be a sheet of polymeric material, asheet of treated paper, for example a polymer coated paper or a polymerimpregnated paper, or a sheet of metallic foil. The wrapper may be asheet of hydrophobic material such as a wax coated paper. In anembodiment, a liquid impervious wrapper may be formed from, or include,an aluminium laminate paper, a class of paper that is well-known in theconfectionary industry and used for an inner liner in tobacco boxes. Theliquid impervious wrapper may be referred to as a liquid impermeablewrapper.

In one embodiment, the article is configured to be suitable for use withan electrically-operated aerosol-generating device. The article may be aconsumable article having an outlet end, a distal end upstream from theoutlet end, and a mid-point located an approximately equal distancebetween the outlet end and the distal end. The article may include aliquid retention medium, at least a portion of which may be locatedbetween the distal end and the mid-point.

In one embodiment, the article may include a liquid aerosol-formingsubstrate contained within a frangible capsule, where the frangiblecapsule may be located between the distal end and the mid-point. Thearticle may be configured such that, during use, air can be drawnthrough the article from the distal end to the outlet end.

In an embodiment, the liquid aerosol-forming substrate may be releasablycontained within the frangible capsule and the liquid retention mediummay be located in proximity to the frangible capsule for retaining theliquid aerosol-forming substrate within the article after its releasefrom the frangible capsule.

The liquid aerosol-forming substrate may, alternatively, be incorporatedinto the liquid retention medium immediately prior to use. For example,a dose of liquid aerosol-forming substrate may be injected into theliquid retention medium immediately prior to use.

In one embodiment, the article may include a first volatile liquidsubstrate contained within a first frangible capsule, and a secondvolatile liquid substrate contained within a second frangible capsule.The first and second frangible capsules may be located between thedistal end and the mid-point. The article may be configured such that,during use, air may be drawn through the article from the distal end tothe outlet end.

In an embodiment, the first volatile liquid substrate may be releasablycontained within the first frangible capsule and the liquid retentionmedium may be located in proximity to the first frangible capsule forretaining the first volatile liquid substrate within the article afterit may be released from the first frangible capsule. In an embodiment,the second volatile liquid substrate may be releasably contained withinthe second frangible capsule and the liquid retention medium may belocated in proximity to the second frangible capsule for retaining thesecond volatile liquid substrate within the article after its releasefrom the second frangible capsule.

The article may include a liquid aerosol-forming substrate. The firstvolatile liquid substrate may be a liquid aerosol-forming substrate, ormay be a constituent part of a liquid aerosol-forming substrate, such asa liquid aerosol former or a nicotine source. The second volatile liquidsubstrate may also be a liquid aerosol-forming substrate, or may be aconstituent part of a liquid aerosol-forming substrate, such as anaerosol former or a nicotine source.

The liquid first volatile substrate may be a first liquidaerosol-forming substrate and the second liquid volatile substrate maybe a second liquid aerosol-forming substrate, where the first liquidaerosol-forming substrate may have a different composition to the secondliquid aerosol-forming substrate. This may provide two differentsensorial experiences using the same article. However, the first liquidaerosol-forming substrate may have the same composition as the secondliquid aerosol-forming substrate.

The first volatile liquid substrate may be a constituent part of aliquid aerosol-forming substrate and the second volatile liquidsubstrate may be another constituent part of the aerosol-formingsubstrate, where the first volatile substrate and the second volatilesubstrate may combine to form the liquid aerosol-forming substrate.

The heated aerosol-generating article may be a consumable that may beconsumed by coupling or engaging with an aerosol-generating device, andmay be an electrically-operated aerosol-generating device. The articlemay be removably couplable with the aerosol-generating device. Thearticle may be used once or twice and then disposed of. A number of usesmay depend on a number of frangible capsules provided. A method of usingthe heated aerosol-generating article may include the steps of couplingthe article to an aerosol-generating device, activating a heatingstructure of the aerosol-generating device, and drawing air through theheated aerosol-generating article. Liquid aerosol-forming substrateretained within the aerosol-generating article may then be vaporized byheat energy supplied by the heating structure and condensed to form anaerosol entrained in the air. When the aerosol-forming substrate mayhave been consumed, the article may be removed from the device. In anembodiment, the method may include steps of releasing the liquidaerosol-forming substrate from a frangible capsule, such that it may beretained by the liquid retention medium of the article, coupling thearticle to an electrically-operated aerosol-generating device,activating a heating structure of the electrically-operatedaerosol-generating device, and drawing air through the article, wherethe liquid aerosol-forming substrate may be vaporized by heat energysupplied by the heating structure and condensed to form an aerosolentrained in the air. In one embodiment, a method may include steps ofreleasing at least one of the first volatile liquid substrate from afirst frangible capsule and the second liquid volatile substrate from asecond frangible capsule such that it may be retained by the liquidretention medium of the article, coupling the article to anelectrically-operated aerosol-generating device, activating a heatingstructure of the electrically-operated aerosol-generating device, anddrawing air through the article, the liquid retained by the liquidretention medium being vaporized by heat energy supplied by the heatingstructure and condensing to form an aerosol entrained in the air.

In an embodiment, the heating structure may heat air that may be drawninto the heated aerosol-generating device, the heated air passing overor through the liquid retention medium of the article to vaporize theliquid aerosol-forming substrate and allow formation of an aerosol. Theair may be heated to a temperature of about 200° C. to 220° C. beforepassing over or through the liquid retention medium. In an embodiment,the air with entrained volatile elements may subsequently cool to atemperature of about 100° C. within the article, allowing the volatileelements to condense and form an aerosol. The heating structure mayalternatively heat the liquid retention medium by conduction orradiation in order to vaporize the liquid aerosol-forming substrate andallow formation of an aerosol.

Where the first liquid volatile substrate includes a first liquidaerosol-forming substrate and the second liquid volatile substrateincludes a second liquid aerosol-forming substrate, a method of usingthe heated aerosol generating article may include: releasing the firstliquid aerosol-forming substrate from the first frangible capsule suchthat it may be retained by the liquid retention medium; coupling theheated aerosol-generating article to an electrically-operatedaerosol-generating device; activating a heating structure of theelectrically-operated aerosol-generating device; drawing air through theheated aerosol-generating device, the first liquid aerosol-formingsubstrate being vaporized by heat energy supplied by the heatingstructure and condensing to form an aerosol entrained in the air;uncoupling the heated aerosol-generating article from the electricallyoperated aerosol-generating device; releasing the second liquidaerosol-forming substrate from the second frangible capsule such that itmay be retained by the liquid retention medium; coupling the heatedaerosol-generating article to the electrically-operatedaerosol-generating device; activating the heating structure of theelectrically-operated aerosol-generating device; and drawing air throughthe heated aerosol-generating device, the second liquid aerosol-formingsubstrate being vaporized by heat energy supplied by the heatingstructure and condensed to form an aerosol entrained in the air.

Where the first liquid volatile substrate includes a first constituentof a liquid aerosol-forming substrate and the second liquid volatilesubstrate includes a second constituent of the liquid aerosol-formingsubstrate, a method of using the heated aerosol-generating article mayinclude: releasing the first liquid volatile substrate from the firstfrangible capsule such that it may be retained by the liquid retentionmedium; releasing the second liquid volatile substrate from the secondfrangible capsule such that it may be retained by the liquid retentionmedium, and combining with the first liquid volatile substrate to form aliquid aerosol-forming substrate; coupling the heated aerosol-generatingarticle to an electrically-operated aerosol-generating device;activating a heating structure of the electrically-operatedaerosol-generating device; and drawing air through the heatedaerosol-generating device, the liquid aerosol-forming substrate beingvaporized by heat energy supplied by the heating structure and condensedto form an aerosol entrained in the air.

In an embodiment, the heating structure may heat air that may be drawninto the heated aerosol-generating device, the heated air passing overor through the liquid retention medium to allow formation of an aerosol.However, the heating structure may heat the liquid retention medium byconduction or radiation to allow formation of an aerosol.

As the article may be intended to be disposed after one or two uses, thehygiene issues that may be associated with typical e-cigarette systemsmay be overcome. Furthermore, the liquid aerosol-forming substrate maynot directly contact a heating element and, thus, problems withoverheating of the aerosol-forming substrate may not occur. The liquidimpervious wrapper, if provided, may help to prevent leakage of liquidaerosol-forming substrate. Articles may be produced with a wide range ofdifferent liquid aerosol-forming substrate compositions, therebyproviding a wide range of flavors and experiences that may be providedby e-cigarette systems. In particular, where a first volatile liquidsubstrate may include a first liquid aerosol-forming substrate and asecond volatile liquid substrate may include a second liquidaerosol-forming substrate, the article may be provided with multipleliquid aerosol-forming substrate compositions, and thereby providemultiple flavors and experiences. In an embodiment, the articles may beconsumed using aerosol-generating devices configured for heatingaerosol-generating articles including solid aerosol-forming substrates.Thus, an adult vaper may select either a tobacco containing heatedaerosol-generating article or select an article containing a liquidaerosol-forming substrate.

As used herein, the term “volatile substrate” refers to anaerosol-forming substrate or a constituent part of an aerosol-formingsubstrate.

As used herein, the term “aerosol-forming substrate” refers to asubstrate capable of releasing volatile compounds that may form anaerosol. An aerosol-forming substrate may be solid or liquid or compriseboth solid and liquid elements.

As used herein, the term “liquid aerosol-forming substrate” refers to anaerosol-forming substrate that may be in a liquid rather than a solidform. A liquid aerosol-forming substrate may be at least partiallyabsorbed by a liquid retention medium. A liquid-aerosol-formingsubstrate may include an aerosol-forming substrate in the form of a gel.Similarly, the term “liquid volatile substrate” may refer to a substratethat is in a liquid rather than a solid form.

As used herein, the term “outlet end” refers to a portion of the heatedaerosol-generating article where aerosol exits the article.

As used herein, the term “distal end” refers to an end of the articlethat opposes the outlet end.

As used herein, the terms “upstream” and “downstream” are used todescribe the relative positions of elements, or portions of elements, ofthe heated aerosol-generating article in relation to the direction thatair may be drawn through the article or system during use. The outletend of the article may also be referred to as the downstream end, andthe distal end of the article may also be referred to as the upstreamend. Elements, or portions of elements, of the article may be describedas being upstream or downstream of one another based on their relativepositions between the mouth or downstream end and the distal or upstreamend.

As used herein, the term “liquid-impervious” refers to the wrapper, andmay indicate that aqueous liquids may not pass through the wrapper undertypical operating conditions.

As used herein, the term ‘sheet’ denotes a laminar element that may havea width and length substantially greater than the thickness thereof. Thewidth of a sheet may be greater than 10 mm, or may be greater than 20 mmor 30 mm.

As used herein, the term ‘longitudinal’ is used to describe thedirection between the upstream end and the downstream end of theaerosol-generating article or aerosol-generating device, and the term‘transverse’ may be used to describe the direction perpendicular to thelongitudinal direction.

As used herein, the term ‘diameter’ is used to describe the maximumdimension in the transverse direction of the aerosol-generating articleor aerosol-generating device. As used herein, the term ‘length’ may beused to describe the maximum dimension in the longitudinal direction.

As used herein, the term “liquid retention medium” refers to an elementthat may be capable of releasably retaining a liquid aerosol-formingsubstrate. The liquid retention medium may be, or may comprise, a porousor fibrous material that may absorb or otherwise retain a liquidaerosol-forming substrate that may be brought into contact with whileallowing the liquid aerosol-forming substrate to be released byvaporization.

As used herein, the term “frangible capsule” refers to a capsule thatmay be capable of containing a liquid aerosol-forming substrate andreleasing the liquid aerosol-forming substrate when broken or ruptured.The frangible capsule may be formed from, or comprise, a brittlematerial that may be easily broken to release its liquid aerosol-formingsubstrate contents. For example the capsule may be broken by externalforce such as finger pressure, or by contact with a piercing orrupturing element.

The heated aerosol-generating article may be substantially cylindricalin shape. The aerosol-generating article may be substantially elongate.The aerosol-generating article may have a length and a circumferencesubstantially perpendicular to the length. The liquid retention mediummay be substantially cylindrical in shape. The liquid retention mediummay be substantially elongate. The liquid retention medium may also havea length and a circumference substantially perpendicular to the length.

The aerosol-generating article may have an external diameter of betweenapproximately 5 millimetres and approximately 12 millimetres, forexample of between approximately 6 millimetres and approximately 8millimetres. In an embodiment, the aerosol-generating article may havean external diameter of 7.2 millimetres+/−10 percent.

The aerosol-generating article may have a total length betweenapproximately 25 mm and approximately 100 mm. The aerosol-generatingarticle may have a total length between approximately 30 mm andapproximately 100 mm. In one embodiment, the aerosol-generating articlemay have a total length of approximately 45 mm. In another embodiment,the aerosol-generating article may have a total length of approximately33 mm.

The liquid retention medium may have a length of between about 7 mm andabout 20 mm, for example between 8 mm and 15 mm. In one embodiment, theliquid retention medium may have a length of approximately 10 mm.

The heated aerosol-generating article may include a plurality ofelements assembled by, or circumscribed by, a wrapper in the form of arod. For example, the article may include the liquid retention medium,and a mouthpiece located downstream of the liquid retention medium. Thewrapper may include indicators, such as markings at positions along itslength to indicate the location of the frangible capsule or of the firstand second frangible capsules. The indicators may indicate where toapply pressure to rupture or break the frangible capsule, or the firstfrangible capsule and the second frangible capsule respectively.

The mouthpiece may be located at the outlet end of the article. Themouthpiece may include a filter. The filter may be formed from one ormore suitable filtration materials. Many such filtration materials maybe well-known in the art. In one embodiment, the mouthpiece may includea filter formed from cellulose acetate tow.

The article may include a porous or air-permeable plug located at thedistal end of the article. Such a plug may act to help retain the liquidaerosol-forming substrate within the article. The plug may have anexternal diameter of a diameter of between approximately 5 millimetresand approximately 10 millimetres, for example of between approximately 6millimetres and approximately 8 millimetres. In an embodiment, the plughas an external diameter of 7.2 millimetres+/−10%.

The plug may have a length of between approximately 2 millimetres andapproximately 10 millimetres. For example, the mouthpiece may have alength of from about 3 mm to about 5 mm.

The article may include an aerosol-forming section or an aerosol-coolingsection. The plurality of elements may be co-axially aligned andassembled within the wrapper. The wrapper may be a traditional cigarettepaper. The wrapper may be a polymeric film or a coated paper. Thewrapper may be liquid-impervious.

The liquid retention medium may include an absorbent material, forexample an absorbent polymeric material. Examples of suitable liquidretention materials include fibrous polymers and porous polymers such asopen-cell foams. The liquid retention medium may include a fibrouscellulose acetate or a fibrous cellulose polymer. The liquid retentionmedium may include a porous polypropylene material. Suitable materialscapable of retaining a liquid may be well-known to a skilled person inthe art.

The liquid retention medium may be either located within an air-flowpath through the heated aerosol-generating article or may define atleast a portion of an air-flow path through the aerosol-generatingarticle. In an embodiment, one or more holes defined through the liquidretention medium may define a portion of the air-flow path through theheated aerosol-generating article between the distal end of the articleand the outlet end of the article.

The liquid retention medium may be in the form of a tube having acentral lumen. Walls of the tube may then be formed from, or comprise, asuitable liquid-retention material.

The heated aerosol-generating article may include a liquidaerosol-forming substrate contained within a frangible capsule. Theheated aerosol-generating article may include liquid volatile substratescontained within frangible capsules. The frangible capsule or capsulesmay be spheroid, for example spherical or ovoid, having a maximumdimension of between 2 mm and 8 mm, for example between 4 mm and 6 mm.The frangible capsule or capsules may contain a volume of between 20 and300 microliters, for example between 30 and 200 microliters. Such arange may provide between 10 and 150 puffs of aerosol.

In an embodiment, the liquid retention medium may be capable ofabsorbing between 105% and 110% of the total volume of liquid containedwithin the frangible capsule. This may help to prevent leakage of liquidaerosol-forming substrate from the article after the frangible capsulehas been broken to release its contents. The liquid retention medium maybe between 90% and 95% saturated after release of the liquidaerosol-forming substrate from the frangible capsule.

The frangible capsules may have a brittle shell, or may be shaped tofacilitate rupture when subjected to external force. The frangiblecapsules may be configured to be ruptured by application of externalforce. For example, the frangible capsules may be configured to ruptureat a specific defined external force, thereby releasing theliquid-aerosol-forming substrate. The frangible capsules may beconfigured with a weakened or brittle portion of its shell to facilitaterupture. The frangible capsules may be arranged for engagement with apiercing element for breaking the capsule and releasing the liquidaerosol-forming substrate. The frangible capsules may have a burststrength of between about 0.5 and 2.5 kilograms force (kgf), for examplebetween 1.0 and 2.0 kgf.

The shell of the frangible capsules may include a suitable polymericmaterial, for example a gelatin based material. The shell of thecapsules may include a cellulose material or a starch material.

In an embodiment, the frangible capsule may be located adjacent to theliquid retention medium within the article such that theliquid-aerosol-forming substrate may be released from the frangiblecapsule and may contact and be retained by the liquid retention medium.The frangible capsule may be located within the liquid retention medium.For example, the liquid retention medium may be in the form of a tubehaving a lumen and the frangible capsule containing the liquidaerosol-forming substrate may be located within the lumen of the tube.

In one embodiment, the frangible capsules may be located adjacent to theliquid retention medium within the article such that the liquid volatilesubstrate may be released from the frangible capsule, and may contactand be retained by the liquid retention medium. The frangible capsulesmay be located within the liquid retention medium. For example, theliquid retention medium may be in the form of a tube having a lumen andthe frangible capsules containing the liquid volatile substrate may belocated within the lumen of the tube.

In an embodiment, the heated aerosol-generating article may include oneor two frangible capsules including liquid volatile substrates. However,the heated aerosol-generating article may include any number offrangible capsules. The heated aerosol-generating article may includetwo or more frangible capsules comprising liquid volatile substrates.

The heated aerosol-generating article may include an aerosol generationsection located downstream of the liquid retention medium. In use, theliquid aerosol-forming substrate may be vaporized and volatile elementsof the substrate may be drawn downstream from the liquid retentionmedium. The volatile elements may then cool in the aerosol formingsection to form the inhalable aerosol. In an embodiment, the air withentrained volatile elements may cool to a temperature of about or below100° C. within the aerosol generation section. The aerosol formingsection may be defined by a space within the article, or by the lumen ofa tube within the article. The aerosol forming section may include anaerosol-cooling element, for example an aerosol-cooling elementincluding a gathered sheet of polymeric material. A suitableaerosol-cooling element is described above.

As mentioned above, the article may include a liquid aerosol-formingsubstrate. In an embodiment with two capsules, the first volatile liquidsubstrate may be a liquid aerosol-forming substrate or may be aconstituent part of a liquid aerosol-forming substrate, such as a liquidaerosol former or a nicotine source. The second volatile liquidsubstrate may also be a liquid aerosol-forming substrate or may be aconstituent part of a liquid aerosol-forming substrate, such as anaerosol former or a nicotine source. Where the first volatile liquidsubstrate is a constituent part of a liquid aerosol-forming substrate,the second volatile liquid substrate may be another constituent part ofthe aerosol-forming substrate and the combination of the first volatilesubstrate and the second volatile substrate may form the liquidaerosol-forming substrate.

The liquid aerosol-forming substrate may include water. In anembodiment, the liquid aerosol-forming substrate may also include anaerosol former such as propylene glycol or glycerine. The liquidaerosol-forming substrate may include a flavorant. The liquidaerosol-forming substrate may further include an active ingredient suchas nicotine. In an embodiment, the liquid-aerosol-forming substrate mayhave a water content of between 10 and 25 weight percent, or for examplebetween 12 and 20 weight percent. Water may be required to form asuitable inhalable aerosol. The liquid aerosol-forming substrate mayinclude a nicotine solution. The liquid aerosol-forming substrate mayinclude a tobacco-containing material including volatile tobacco flavorcompounds which may be released from the liquid upon heating. The liquidaerosol-forming substrate may include a non-tobacco material. The liquidaerosol-forming substrate may include solvents, ethanol, plant extractsand natural or artificial flavors.

As used herein, the term “aerosol former” refers to any suitable knowncompound or mixture of compounds that, in use, facilitates formation ofa dense and stable aerosol. An aerosol former may be substantiallyresistant to thermal degradation at the operating temperature of theaerosol-generating article. Suitable aerosol formers may be well-knownin the art and may include, but are not limited to: polyhydric alcohols,such as triethylene glycol, 1,3-butanediol and glycerine; esters ofpolyhydric alcohols, such as glycerol mono-, di- or triacetate; andaliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyldodecanedioate and dimethyl tetradecanedioate. In an embodiment, aerosolformers may be polyhydric alcohols or mixtures thereof, such astriethylene glycol, 1,3-butanediol and glycerine.

In an embodiment, in a heated aerosol-generating system, an airflow pathmay be defined when the heated aerosol-generating article may be coupledto the aerosol-generating device. The air flow path may include a pointat which air enters the aerosol-generating device, a point at which airpasses into the distal end of the heated aerosol-generating article, apoint at which air passes over the liquid retention medium, and a pointat which air passes out of the outlet end of the heatedaerosol-generating article. In an embodiment, a system may include anaerosol-generating device acting to heat air at a point between entryinto the aerosol-generating device and passing over the liquid retentionmedium. This may allow heated air to vaporize a liquid aerosol-formingsubstrate retained by the liquid retention medium. Heating of the airmay be accomplished by a heater such as a heating coil that may belocated within the airflow path, and may act to directly heat the airprior to that air passing over the liquid retention medium.

The heated aerosol-generating system may include an air permeable heataccumulator or heat diffuser that may be arranged in the air flow pathto heat air. The term heat diffuser is defined below. The heat diffusermay interact with a heater and take on heat energy. The heat energy maythen transfer to air that may pass through the heat diffuser. A heatdiffuser may be an element having a high surface area and high porosity.Air may be able to flow through the heat diffuser without undergoing asignificant pressure drop. Examples of suitable heat diffusers may be aporous metallic foam or a porous ceramic foam element arranged both inthermal contact with a heater and within the air flow path of the heatedaerosol-generating system.

A heat diffuser may be a removable element of a heatedaerosol-generating system. For example, heat diffuser may be in the formof a removably couplable element that may engage with an aerosolgenerating device to alter the manner in which the aerosol generatingdevice heats aerosol generating articles. As an example, an aerosolgenerating device may include an insertable heating element forinsertion into a solid aerosol forming substrate of a heatedaerosol-generating article. The heating element may contact the solidaerosol-forming substrate and heat it to generate an aerosol. A heatdiffuser may be configured to engage with the insertable heatingelement. The heat diffuser may then be heated by the heating element andheat air that may pass through the heating element. The heated air maythen volatilize an aerosol-forming substrate of a heatedaerosol-generating article that may be located downstream of the heatdiffuser. In this way, the manner in which the aerosol-generating devicemay heat an aerosol-forming substrate may be changed from direct contactto indirect heating of air. The same aerosol-generating device may thenbe used to heat different types of aerosol-generating article.

In an embodiment, a system may include a heated aerosol-generatingdevice, at least one heated aerosol-generating article as describedabove that may have a liquid aerosol-forming substrate, and at least oneheated aerosol-forming substrate that may have a solid aerosol-formingsubstrate, for example an aerosol-forming substrate made fromhomogenized tobacco material. In an embodiment, the system may furtherinclude a removably couplable heat diffuser for engagement with theaerosol-generating device to change the manner in which theaerosol-generating device may provide heat to the aerosol-formingsubstrate.

In an embodiment, the aerosol-generating device may be a portable orhandheld aerosol-generating device that may be comfortable to holdbetween the fingers of a single hand.

The aerosol-generating device may be substantially cylindrical in shape.The aerosol-generating device may have a length of between approximately70 millimetres and approximately 120 millimetres.

The device may include a power supply for supplying electrical power tothe electric heating element. The power supply may be any suitable powersupply, for example a DC voltage source such as a battery. In oneembodiment, the power supply may be a Lithium-ion battery.Alternatively, the power supply may be a Nickel-metal hydride battery, aNickel cadmium battery, or a Lithium based battery, for example aLithium-Cobalt, a Lithium-Iron-Phosphate, Lithium Titanate or aLithium-Polymer battery.

The controller may be a simple switch. Alternatively, the controller maybe electric circuitry and may include one or more microprocessors ormicrocontrollers.

In another embodiment, a heated aerosol-generating article may be usedwith an electrically-operated aerosol-generating device. The heatedaerosol-generating article may be a consumable article having an outletend, a distal end upstream from the outlet end, and a mid-point that maybe located an equal distance between the outlet end and the distal end.The article may include: a liquid aerosol-forming substrate containedwithin a frangible capsule, where the frangible capsule may be locatedbetween the distal end and the mid-point, and a liquid retention medium,at least a portion of which may be located between the distal end andthe mid-point, in which the article may be configured such that, duringuse, air may be drawn through the article from the distal end to theoutlet end.

In an embodiment of the heated aerosol-generating article, one or moreof the following features may be used:

the liquid aerosol-forming substrate may be releasably contained withinthe frangible capsule and the liquid retention medium may be located inproximity to the frangible capsule for retaining the liquidaerosol-forming substrate within the article after its release from thefrangible capsule;

the heated aerosol-generating article may include a plurality ofelements assembled by a wrapper in the form of a rod;

the frangible capsule may be located within the liquid retention mediumin the heated aerosol-generating article;

the liquid retention medium may be in the form of a tube having a lumenand the frangible capsule may be located within the lumen of the tube;

the liquid retention structure may include an absorbent polymericmaterial;

the frangible capsule may be configured to be ruptured by application ofexternal force;

the frangible capsule may be configured to be pierced by a piercingelement;

the heated aerosol-generating article may include a cooling sectionlocated downstream from the liquid retention element;

the liquid aerosol-forming substrate may include between 10 weightpercent and 25 weight percent water, an aerosol former, and at least oneflavorant;

the heated aerosol-generating article may include a mouthpiece filterlocated at the outlet end of the article;

the heated aerosol-generating article may include a porous plug locatedat the distal end of the article;

In an embodiment of the heated aerosol-generating system, the system mayinclude a heated aerosol-generating article according to the secondaspect of the invention, and an electrically-operated aerosol-generatingdevice, the electrically-operated aerosol-generating device includingstructure for heating the aerosol-forming substrate so as to form anaerosol. The heated aerosol-generating system may include a piercingelement for piercing the frangible capsule.

A method of using a heated aerosol generating article may include thesteps of: releasing the liquid aerosol-forming substrate from thefrangible capsule such that it may be retained by the liquid retentionmedium; coupling the heated aerosol-generating article to anelectrically-operated aerosol-generating device; activating a heatingstructure of the electrically-operated aerosol-generating device; anddrawing air through the heated aerosol-generating article, the liquidaerosol-forming substrate being vaporized by heat energy supplied by theheating structure and condensing to form an aerosol entrained in theair. The heating structure may heat air that may be drawn into theheated aerosol-generating article, the heated air may pass over orthrough the liquid retention medium to allow formation of an aerosol.The heating structure may heat the liquid retention medium by conductionor radiation to allow formation of an aerosol.

In another embodiment, a heated aerosol-generating article may include aplurality of elements that may be coaxially aligned and assembled withina wrapper. The article may have an outlet end and a distal end upstreamfrom the outlet end, and the article may include: a liquidaerosol-forming substrate, and a liquid retention medium that may retainthe liquid aerosol-forming substrate, in which the wrapper may be formedfrom a sheet of liquid-impervious material.

In an embodiment of the heated aerosol-generating article, one or moreof the following features may be used:

the liquid aerosol-forming substrate may be releasably contained withina frangible capsule, the frangible capsule may be located in proximityto the liquid retention medium for retaining the liquid aerosol-formingsubstrate within the article after its release from the frangiblecapsule;

the frangible capsule may be located within the liquid retention medium;

the liquid retention medium may be in the form of a tube having a lumenand the frangible capsule may be located within the lumen of the tube;

the liquid retention medium may include an absorbent polymeric material;

the frangible capsule may be configured to be ruptured by application ofexternal force;

the frangible capsule may be configured to be pierced by a piercingelement;

the heated aerosol-generating article may include a cooling sectionlocated downstream from the liquid retention element;

the liquid aerosol-forming substrate may include between 10 weightpercent and 25 weight percent water, an aerosol former, and at least oneflavorant;

the heated aerosol-generating article may include a mouthpiece filterlocated at the outlet end of the article;

the heated aerosol-generating article may include a plug located at thedistal end of the article, the article being configured such that airmay be drawn into the article at or adjacent to the distal end, throughthe article, and out of the outlet end of the article;

the wrapper may be a sheet of polymeric material, a sheet of treatedpaper, or a sheet of metallic foil.

In an embodiment of the heated aerosol-generating system, the system mayinclude a heated aerosol-generating article according to anotherembodiment, and an electrically-operated aerosol-generating device, theelectrically-operated aerosol-generating device including structure forheating the aerosol-forming substrate so as to form an aerosol.

A method of using a heated aerosol generating article according toanother embodiment may include the steps of: coupling the heatedaerosol-generating article to an electrically-operatedaerosol-generating device; activating a heating structure of theelectrically-operated aerosol-generating device; and drawing air throughthe heated aerosol-generating article, the liquid aerosol-formingsubstrate being vaporized by heat energy supplied by the heatingstructure and condensing to form an aerosol entrained in the air. Theliquid aerosol-forming substrate may be contained within a frangiblecapsule, and the method may further include the step of releasing theliquid aerosol-forming substrate from the frangible capsule such that itmay be retained within the article by the liquid retention medium.

In another embodiment, a heated aerosol-generating article for use withan electrically-operated aerosol-generating device may include aconsumable article having an outlet end, a distal end upstream from theoutlet end, and a mid-point located an equal distance between the outletend and the distal end, where the article may include: a first volatileliquid substrate contained within a first frangible capsule, thefrangible capsule being located between the distal end and themid-point; a second volatile liquid substrate contained within a secondfrangible capsule, the second frangible capsule being located betweenthe distal end and the mid-point; and a liquid retention medium, atleast a portion of which may be located between the distal end and themid-point, in which the article may be configured such that, during use,air may be drawn through the article from the distal end to the outletend.

In some variants of the heated aerosol-generating article according toanother embodiment, one or more of the following features may be used:

the article may include a liquid aerosol-forming substrate, the firstvolatile liquid substrate including a first constituent of the liquidaerosol-forming substrate and the second volatile liquid substrateincluding a second constituent of the liquid aerosol-forming substrate;

the liquid aerosol-forming substrate including between 10 weight percentand 25 weight percent water, an aerosol former, and at least oneflavorant;

the first volatile liquid substrate including a first liquidaerosol-forming substrate and the second volatile substrate including asecond liquid aerosol-forming substrate;

the first volatile liquid substrate may be releasably contained withinthe first frangible capsule and the liquid retention medium may belocated in proximity to the first frangible capsule for retaining thefirst volatile liquid substrate within the article after it may bereleased from the first frangible capsule, and the second volatileliquid substrate may be releasably contained within the second frangiblecapsule and the liquid retention medium may be located in proximity tothe second frangible capsule for retaining the second volatile liquidsubstrate within the article after it may be released from the secondfrangible capsule;

the heated aerosol-generating article may include a plurality ofelements assembled by a wrapper in the form of a rod;

the first and second frangible capsules may be located within the liquidretention medium;

the liquid retention medium may be in the form of a tube having a lumenand the first and second frangible capsules may be located within thelumen of the tube;

the first and second frangible capsules may be coaxially aligned in thelumen of the tube;

the liquid retention medium may include an absorbent polymeric material;

at least one of the first and second frangible capsules may beconfigured to be ruptured by application of external force;

at least one of the first and second frangible capsules may beconfigured to be pierced by a piercing element;

the heated aerosol-generating article may include a cooling sectionlocated downstream from the liquid retention medium;

the heated aerosol-generating article may include a mouthpiece filterlocated at the outlet end of the article;

the heated aerosol-generating article may include a porous plug locatedat the distal end of the article.

In an embodiment of the heated aerosol-generating system, the system mayinclude a heated aerosol-generating article as described above, and anelectrically-operated aerosol-generating device, theelectrically-operated aerosol-generating device including structure forheating at least one of the first volatile liquid substrate and thesecond volatile liquid substrate that may be retained in the liquidretention medium so as to form an aerosol. The heated aerosol-generatingsystem may include a piercing element for piercing at least one of thefrangible capsules.

According to another embodiment, an electrically operatedaerosol-generating device and a heat diffuser may be configured for usewith an aerosol-generating article. The aerosol-generating article mayinclude an aerosol-forming substrate and may have an outlet end and adistal end upstream from the outlet end. The electrically operatedaerosol-generating device may include an electric heating element and ahousing having a cavity configured to receive the distal end of theaerosol-generating article. The heat diffuser may be removably couplableto the aerosol-generating device and may include a non-combustibleporous body for absorbing heat from the electric heating element whenthe heat diffuser may be coupled to the aerosol-generating device suchthat, in use, air may be drawn through the aerosol-generating articlefrom the distal end to the outlet end may be heated by the heat absorbedin the porous body.

According to another embodiment, an electrically operatedaerosol-generating device for an aerosol-generating may include: ahousing having a cavity that may be configured to receive the distal endof an aerosol-generating article; an electric heating element; and aheat diffuser including a non-combustible, air permeable main body forabsorbing and storing heat from the electric heating element such that,in use, air may be drawn through the main body of the heat diffuser andmay be heated by heat stored in the main body.

The articles described above may be used any combination of the systemsdescribed above.

Features described in relation to one or more aspects may equally beapplied to other embodiments.

Structural Embodiments:

FIG. 1 illustrates a longitudinal cross-section of a heat diffuser 100of an aerosol-generating system, in accordance with an exampleembodiment. The heat diffuser 100 may include a porous body 110 that maybe in the form of a cylindrical plug of thermally conductive material.The porous body 110 may have an upstream or distal end 120, and adownstream or proximal end 130, opposite to the upstream end 120. Thebody 110 may define a cavity that may be in the form of a slot 140 thatmay be in the upstream end 120 of the porous body 110, and may bearranged to receive a blade-shaped heating element, as discussed belowin relation to FIG. 3. The pores in the porous body 110 may beinterconnected to form a plurality of air flow passages extendingthrough the porous body 110 from its upstream end 120 to its downstreamend 130.

FIGS. 2A to 2H illustrate embodiments of an aerosol-generating article.The articles shown in FIGS. 2A-H may be used with the aerosol-generatingdevices described below, or with other aerosol-generating devices. Thearticles shown in FIGS. 2A-H may also be used with theaerosol-generating systems described below, or with otheraerosol-generating systems.

FIG. 2A illustrates a longitudinal cross-section of anaerosol-generating article 200 a that may be used with the heat diffuser100 of FIG. 1, in accordance with an example embodiment. An aerosolgenerating article may also be called a heated aerosol-generatingarticle. The aerosol-generating article 200 a may include three elementsarranged in coaxial alignment: a tubular liquid retention medium 210 a,an aerosol-cooling element 220 a, and a mouthpiece 230 a. The aerosolcooling element 220 a may also be called an aerosol-generating section.The mouthpiece 230 a may also be called a mouthpiece filter. Each ofthese three elements may be a substantially cylindrical element, witheach having substantially the same diameter. These three elements may bearranged co-axially, and circumscribed by an outer wrapper 240 a, toform a cylindrical rod. The outer wrapper 240 a may be non-porous. Theouter wrapper 240 a may be liquid-impervious.

The aerosol-generating article 200 a may have a distal or upstream end250 a, and a proximal or outlet end 260 a, opposite to the upstream end250 a. Once assembled, the total length of the aerosol-generatingarticle 200 a may be about 33 mm about 45 mm, and the diameter may beabout 7.2 mm.

The liquid retention medium 210 a may be located at the extreme distalor upstream end 250 a of the aerosol-generating article 200 a. In anembodiment, the article 200 a may include a frangible capsule 212 a thatmay be located within the lumen 214 a of the liquid retention medium 210a. The frangible capsule 212 a may contain a liquid aerosol-formingsubstrate 216 a.

The tubular liquid retention medium 210 a may have a length of 8 mm, andmay be formed from fibrous cellulose acetate material. The liquidretention medium 210 a may have a capacity to absorb 35 microliters ofliquid. The lumen 214 a of the tubular liquid retention medium 210 a mayprovide an air flow path through the liquid retention medium 210 a, andalso may act to position the frangible capsule 212 a. The material ofthe liquid retention medium 210 a may be any other suitable fibrous orporous material.

The frangible capsule 212 a may be shaped as an oval spheroid, and mayhave a long dimension of the oval aligned with the axis of the lumen 214a. The oval spheroid shape of the capsule may mean that it may be easierto break, than if it was circular spherical in shape, but other shapesof capsule may also be used. The capsule 212 a may have an outer shellincluding a gelatin based polymeric material, surrounding a liquidaerosol-forming substrate.

The liquid aerosol-forming substrate 216 a may include propylene glycol,nicotine extract, and 20 weight percent water. A wide range offlavorants may be optionally added. A wide range of aerosol formers maybe used as alternative, or in addition to, propylene glycol. The capsule212 a may be about 4 mm in length, and may contain a volume of about 33microliters of liquid aerosol-forming substrate.

The aerosol-cooling section 220 a may have a length of 18 mm. Theaerosol-cooling section 220 a may include a crimped and gathered sheetof polymeric material 222 a. The sheet of polymeric material 222 a maynot be densely packed, and therefore the aerosol-cooling section 220 amay not cause significant pressure drop in air passing through thesection 220 a. The crimped and gathered sheet of polymeric material 222a may be termed an aerosol-cooling element, and may have a length ofabout 18 mm, an outer diameter of about 7.12 mm, and an inner diameterof about 6.9 mm. In one embodiment, the aerosol-cooling element 220 amay be formed from a sheet of polylactic acid having a thickness of 50mm±2 mm. The sheet of polylactic acid may be crimped and gathered todefine a plurality of channels that may extend along a length of theaerosol-cooling element 220 a. A total surface area of theaerosol-cooling element 220 a may be between 8000 mm² and 9000 mm²,which may be equivalent to approximately 500 mm² per mm length of theaerosol-cooling element 220 a. The specific surface area of theaerosol-cooling element 222 a may be approximately 2.5 mm²/mg and it mayhave a porosity of between 60% and 90% in the longitudinal direction.The polylactic acid may be kept at a temperature of 160 degrees Celsiusor less during use.

Porosity may be defined herein as a measure of unfilled space in a rodincluding material such as an aerosol-cooling element 222 a. Forexample, if a diameter of the rod was 50% unfilled by theaerosol-cooling element 222 a, the porosity would be 50%. Likewise, arod would have a porosity of 100%, if the inner diameter was completelyunfilled, and a porosity of 0% if completely filled. The porosity may becalculated using known methods.

The aerosol-cooling element 220 a may be located immediately downstreamof the liquid retention medium 210 a, where the aerosol-cooling element220 a may directly abut the liquid retention medium 210 a. In use,volatile substances released from the aerosol-forming substrate 216 amay pass along the aerosol-cooling element 220 a, towards the outlet end260 a of the aerosol-generating article 200 a. The volatile substancesmay be cooled within the aerosol-cooling element 220 a, to form anaerosol. In an embodiment, the aerosol-cooling element 220 a may includea crimped and gathered sheet 222 a of polylactic acid circumscribed by awrapper 224 a. The crimped and gathered sheet 222 a of polylactic acidmay define a plurality of longitudinal channels that may extend along alength of the aerosol-cooling element 220 a.

In an alternative embodiment, the aerosol-cooling section 220 a may be ahollow section, such as a hollow tube, and may not include anaerosol-cooling element 220 a. Such an embodiment is described below.

The mouthpiece 230 a may be located immediately downstream of theaerosol-cooling element 220 a, where the mouthpiece 230 a may directlyabut the aerosol-cooling element 220 a. In an embodiment, the mouthpiece230 a may include a cellulose acetate tow filter 232 a of low filtrationefficiency. The mouthpiece filter 230 a may have a length of 7 mm andmay be formed from cellulose acetate tow. Other suitable mouthpiecefilters that are well-known in the art may be used.

To assemble the aerosol-generating article 200 a, the three cylindricalelements described above may be aligned and tightly wrapped within theouter wrapper 240 a. In an embodiment, the outer wrapper 240 a may beformed from a non-porous sheet material. The wrapper 240 a may be aliquid-impervious wrapper, for example a wax-coated paper. Othersuitable no-porous or liquid-impervious materials that are well-knownmay be used, such as for example polymeric films or hydrophobic papers.In an embodiment, the outer wrapper may include a porous material, suchas cigarette paper.

FIGS. 2B to 2D illustrate other embodiments of a heatedaerosol-generating article.

FIG. 2B illustrates a heated aerosol-generating article 200 b having atubular liquid retention medium 210 b and a mouthpiece filter 232 bassembled in abutting relationship within a wrapper 240 b. The article200 b may have a distal end 250 b and an outlet end 260 b. The wrapper240 b may be non-porous or liquid-impervious. The lumen 214 b defined bythe tubular liquid retention medium 210 b may hold a frangible capsule212 b containing a liquid aerosol-forming substrate may be locatedwithin a lumen 214 b of the liquid retention medium 210 b. The overalllength of the article 200 b may be about 30 mm. The liquid retentionmedium 210 b may have a length of 20 mm, and the filter 232 b may have alength of 10 mm. The materials of the liquid retention medium 210 b, thefrangible capsule 212 b, the liquid aerosol-forming substrate 216 b, andthe mouthpiece filter 232 b of the mouthpiece 230 b, may be the same asdescribed above in relation to FIG. 2A.

FIG. 2C illustrates a heated aerosol-generating article 200 c that maybe similar to the article 200 a of FIG. 2A, where like reference numbersare not described again here, for sake of brevity. However, article 200c may differ from article 200 a from the standpoint that article 200 cmay have a rigid hollow mouthpiece 230 c. The mouthpiece 230 c may betubular, and may define a lumen 233 c that may define an air flow path232 c.

FIG. 2D illustrates a heated aerosol-generating article 200 d that maybe similar to the article 200 a (FIG. 2A), where like reference numbersare not described again here, for sake of brevity. However, article 200d may differ from article 200 a from the standpoint that article 200 dmay include a front-plug 251 d that may be disposed at the distal end250 d of the article 200 d. The front-plug 251 d may have a length of 3mm, and may span the distal end 250 d of the article 200 d. The frontplug 251 d may be formed of a highly porous cellulose acetate material,and may provide an air flow path into the article 200 d. The front-plug251 d may help to prevent egress of the liquid aerosol-forming substrate216 d during use of the article 200 d.

FIG. 2E illustrates an embodiment of a heated aerosol-generating article200 e that may be similar to the article 200 a (FIG. 2A), where likereference numbers are not described again here, for sake of brevity.However, article 200 e may differ from article 200 a from the standpointthat article 200 e may include a first volatile liquid substrate 80 ethat may be contained within a first frangible capsule 90 e, and asecond liquid volatile substrate 81 e that may be contained within asecond frangible capsule 91 e. The first frangible capsule 90 e may belocated within a lumen 214 e of the tubular liquid retention medium 210e. The second frangible capsule 91 e may also be located within thelumen 214 e of the tubular liquid retention medium 200 e, and may bearranged co-axially with the first frangible capsule 91 e within thelumen 214 e, such that the first frangible capsule 90 e may be arrangedtowards the distal end 250 e and the second frangible capsule 91 e maybe arranged towards the aerosol-generating section 220 e (closer to theoutlet end 260 e).

The first frangible capsule 90 e may be shaped as an oval spheroid, andmay have the long dimension of the oval aligned with the axis of thelumen 214 e. The oval spheroid shape of the first frangible capsule 90 emay mean that it may be easier to break than if it was circularspherical in shape, but other shapes of capsule may also be used. Thefirst frangible capsule 90 e may have an outer shell including a gelatinbased polymeric material surrounding the liquid aerosol-formingsubstrate 80 e.

The second frangible capsule 91 e may be identical to the firstfrangible capsule 90 e. The second frangible capsule 91 e may also be ofdifferent material or shape than the first frangible capsule 90 e. Thefirst frangible capsule 90 e, or the second frangible capsule 91 e, orboth, may have a different shape, or a different construction, from thatdescribed above.

The first volatile liquid substrate 80 e may include propylene glycol,nicotine extract, and 20 weight percent water. A wide range offlavorants may be optionally added. A wide range of aerosol-formers maybe used as alternative, or in addition to, propylene glycol. The capsule90 e may have a long axis that may be about 4 mm in length, and maycontain a volume of about 33 microliters of the first liquidaerosol-forming substrate 80 e.

The second volatile liquid substrate 81 e also may include propyleneglycol, nicotine extract, and 20 weight percent water, but may include adifferent flavorant, as compared to the first volatile liquid substrate80 e. The second frangible capsule 91 e may have a long axis that may beabout 4 mm in length, and may contain a volume of about 33 microlitersof the second liquid aerosol-forming substrate 81 e.

FIG. 2F illustrates a heated aerosol-generating article 200 f having atubular liquid retention medium 210 f and a mouthpiece filter 232 fassembled in abutting relationship within a non-porous wrapper 240 f. Afirst frangible capsule 90 f that may contain a liquid aerosol-formingsubstrate 80 f may be located within a lumen 214 f of the liquidretention medium 210 f. A second frangible capsule 91 f that may containthe liquid aerosol-forming substrate 81 f may also be located within thelumen 214 f of the liquid retention medium 210 f. The overall length ofthe article 200 f may be about 30 mm. The liquid retention medium 210 fmay have a length of 20 mm, and the filter 232 f may have a length ofabout 10 mm. The materials of the liquid retention medium 210 f, thefirst and second frangible capsules 90 f/91 f, and the mouthpiece filter232 f, may be the same as described above in relation to FIGS. 2A and2E. The liquid aerosol-forming substrate 80 f/81 f may include propyleneglycol, nicotine extract, 20 weight percent water and variousflavorants.

FIG. 2G illustrates a heated aerosol-generating article 200 g that maybe similar to the article 200 e (FIG. 2E), where like reference numbersare not described again here, for sake of brevity. However, article 200g may differ from article 200 e from the standpoint that article 200 gmay include a rigid hollow mouthpiece 230 g. The mouthpiece 230 g may betubular, and may define a lumen 233 g that may define an air flow path232 g.

FIG. 2H illustrates a heated aerosol-generating article 200 h that maybe similar to article 200 e (FIG. 2E), where like reference numbers arenot described again here, for sake of brevity. However, article 200 hmay differ from article 200 e from the standpoint that article 200 h mayinclude a front-plug 251 h that may be disposed at a distal end 251 h ofthe article 200 h. The front-plug 251 h may have a length of 3 mm, andmay span the distal end 250 h of the article 200 h. The front plug 251 hmay be formed of a highly porous cellulose acetate material, and mayprovide an air flow path into the article 200 h. The front-plug 251 hmay help to prevent egress of liquid aerosol-forming substrate 80 hduring use of the article 200 h.

FIG. 3 illustrates an aerosol-generating system 305, in accordance withan example embodiment. The aerosol-generating system 305 may include theheat diffuser 100, the aerosol-generating article 200 a, and anaerosol-generating device 300. In an embodiment, the aerosol generatingsystem 305 may instead include any of the aerosol-generating articles200 b-h described above. The system 305 will now be described inconnection with the aerosol-generating article 200 a. This descriptionmay apply equally to the other aerosol-generating article 200 b-hembodiments.

The aerosol-generating device 300 may include a housing 310 that maydefine a cavity 320 that may receive the heat diffuser 100 and theaerosol-generating article 200 a. The device 300 may further include aheater 330 that may include a base portion 332 and a heating element 334that may be in the form of a heater blade that may penetrate the heatdiffuser 100, so that a portion of the heater blade 334 may extend intothe slot 140 in the porous body 110 when the heat diffuser 100 may bereceived in the cavity 320. The heater blade 334 may include resistiveheating tracks 336 that may resistively heat the heat diffuser 100. Acontroller 340 may include circuitry that controls the operation of thedevice 300, including the supply of electrical current from a powersource 350, such as a battery, to the resistive heating tracks 336 ofthe heater blade 334.

As depicted in FIG. 3, the frangible capsule 212 a (FIG. 2A) may alreadyhave been ruptured, prior to insertion of the article 200 a into thecavity 320 of the device 300, which FIG. 3 illustrates. Thus, the liquidaerosol-forming substrate 216 a is depicted as being already absorbedinto the liquid retention medium 210 a. In an embodiment, the frangiblecapsule 212 a may be ruptured following, or during, insertion of theaerosol-generating article 200 a into the cavity 320 of the device 300.For example, the heat diffuser 100 may have a piercing member at itsdownstream end which may be arranged to engage with and rupture thefrangible capsule 212 a during insertion of the aerosol-generatingarticle 200 a into the cavity 320.

During use, the controller 340 may supply electrical current from thebattery 350 to the resistive heating tracks 336 to heat the heater blade334. Thermal energy may then be absorbed by the porous body 110 of theheat diffuser 100 to heat the porous body 110. Air may be drawn into thedevice 300 through air inlets (not shown), and the air may subsequentlybe drawn through the heat diffuser 100 and along the aerosol-generatingarticle 200 a from the distal end 120 of the heat diffuser 100 to theoutlet end 260 a of the aerosol-generating article 200 a. As air isdrawn through the porous body 110, the air may be heated by the heatabsorbed by the porous body 110 from the heater blade 334, beforepassing through the liquid retention medium 210 a of theaerosol-generating article 200 a to heat the liquid aerosol-formingsubstrate 216 a in the liquid retention medium 210 a. In the event thecontroller 340 is a processor executing software, the processor isconfigured as a special purpose machine to execute the software, storedin a storage medium (e.g., a memory 350 a), to perform the functions ofthe controller 340. In such an embodiment, the processor may include oneor more Central Processing Units (CPUs), digital signal processors(DSPs), application-specific-integrated-circuits (ASICs), fieldprogrammable gate arrays (FPGAs) computers.

During a heating cycle, at least some of the one or more volatilecompounds within the aerosol-generating substrate 216 a may evaporate.The vaporized aerosol-forming substrate may become entrained in the airflowing through the liquid retention medium 210 a, and condense withinthe aerosol-cooling element 220 a and the mouthpiece portion 230 a ofthe system 305 in order to form a generated aerosol, where the aerosolmay exit the aerosol-generating article 200 a at the outlet end 260 a.

FIG. 4 illustrates an aerosol-generating article 400 in accordance withan embodiment. The aerosol-generating article 400 may have similarstructure to the aerosol-generating article 200 a of FIG. 2A, where thesame features are represented using like reference numerals which aregenerally not separately described here for sake of brevity. As with theaerosol-generating article 200 a of FIG. 2A, the aerosol-generatingarticle 400 may include a liquid retention medium 210 a, anaerosol-cooling element 220 a, and a mouthpiece 230 a that may bearranged in coaxial alignment and circumscribed by a non-porous outerwrapper 440 to form a cylindrical rod. However, unlike theaerosol-generating article 200 a of FIG. 2A, the aerosol-generatingarticle 400 may include a heat diffuser 500 at the upstream end 450 ofthe aerosol-generating article 400. The heat diffuser 500 may include aporous body 510 that may be in the form of a cylindrical plug of heatstorage material, such as ceramic foam. The heat diffuser 500 may alsobe circumscribed by the outer wrapper 440, such that the heat diffuser500 may form part of the aerosol-generating article 400. A separation405 may be provided between the downstream end of the heat diffuser 500and the upstream end of the liquid retention medium 210 a to minimize anextent to which the liquid retention medium 210 a may be heated byconduction from the heat diffuser 500.

As the heat diffuser 500 may form part of the aerosol-generating article400, the heat diffuser 500 may be removably coupled to a device (such asdevice 300 of FIG. 3), as an integral part of the aerosol-generatingarticle 400, rather than as two separate elements (as shown in theembodiments of FIGS. 1-3). Use of the aerosol-generating article 400 mayotherwise the same as discussed above, in relation to FIG. 3.

The heat diffuser 500 may also be combined with any of the embodimentsof the aerosol-generating articles shown on FIGS. 2B-H, just as it hasbeen shown combined with the aerosol-generating article 200 a of FIG.2A.

Although the embodiments shown in FIGS. 1-4 illustrate that theaerosol-generating articles 200 a-h/400 may include one or morefrangible capsules, in an embodiment, three or more frangible capsulesmay also be provided. In an embodiment, the articles 200 a-h/400 mayinclude a solid aerosol-forming substrate (such as the substrate 216 aof FIG. 2A), in addition to, or instead of, the frangible capsules.

Furthermore, although the embodiments of FIGS. 1-4 illustrate a heatingelement 334 that may be a heating blade arranged to extend into the slot140/540 of a heat diffuser 100/500, the heating element may be providedas one or more heating elements extending around the periphery of thecavity. Additionally or alternatively, the heating element 334 may be asusceptor located within the heat diffuser. For example, a blade-shapedsusceptor may be located within the heat diffuser, in contact with aporous body. One or both ends of the susceptor may be sharpened orpointed to facilitate insertion into the heat diffuser.

Methods of using a heated aerosol-generating article according toexample embodiments using the aerosol-generating articles shown in FIGS.2A-D will be described with relation to the embodiment of FIG. 2A, forsake of brevity. It should be understood that the heatedaerosol-generating articles disclosed herein are intended to beconsumable items that may be engaged with a separate aerosol-generatingdevice for consumption.

In an example embodiment, a first step of a method of use may be torelease the liquid aerosol-forming substrate 216 a from its frangiblecapsule 212 a. This may be achieved by squeezing the article 200 a inthe region of the capsule 212 a to apply an external force that mayrupture the frangible capsule 212 a. Once ruptured, the liquidaerosol-forming substrate 216 a may be released onto and rapidlyabsorbed by the liquid retention medium 210 a. The article 200 a maythus be primed and ready for engagement with an aerosol-generatingdevice.

Methods of using a heated aerosol-generating article according toexample embodiments using the aerosol-generating article shown in FIGS.2E-H will be described with relation to the embodiment of FIG. 2E, forsake of brevity. The heated aerosol-generating articles disclosed hereinare intended to be consumable items that may be engaged with a separateaerosol-generating device for consumption.

In an example embodiment, a first step may be to release the firstvolatile liquid substrate 80 e from the first frangible capsule 90 e.This may be achieved by squeezing the article 200 e in the region of thefirst frangible 90 e capsule to apply an external force to rupture thefirst frangible capsule 90 e. Once ruptured, the first liquid volatilesubstrate 80 e may be released onto and rapidly absorbed by the liquidretention medium 210 e.

Where the first liquid volatile substrate 80 e is a first liquidaerosol-forming substrate, the article 200 e may thus be primed andready for engagement with an aerosol-generating device. After a firstuse of the aerosol-generating article 200 e, the second liquid volatilesubstrate 81 e may be released from the second capsule 91 e by squeezingthe article in the region of the second capsule 91 e. The article 200 emay thus be primed and ready for engagement with an aerosol-generatingdevice again for a second use of the article.

Where the first liquid volatile substrate 80 e is a constituent of aliquid aerosol-forming substrate, and the second liquid volatilesubstrate 81 e is another constituent of the liquid aerosol-formingsubstrate, the second volatile liquid substrate 81 e may also bereleased from the second frangible capsule 91 e before the article 200 emay be primed and ready for engagement with an aerosol-generatingdevice. Releasing the second volatile liquid substrate 81 e from thesecond frangible capsule 91 e may cause the second volatile liquidsubstrate 81 e to mix with the first volatile liquid substrate 80 e inthe liquid retention medium to form the liquid aerosol-formingsubstrate. This may be achieved by squeezing the article in the regionof the second frangible capsule 91 e to apply an external force torupture the second frangible capsule 91 e. Once ruptured, the secondliquid volatile substrate 81 e may be released onto and rapidly absorbedby the liquid retention medium, where it may mix with the first liquidvolatile substrate 80 e to form the liquid aerosol-forming substrate.

FIG. 5 illustrates a use of an aerosol-generating device 600 havingexternal heating elements 630. This description entails use of thedevice 600 with the aerosol-generating article 200 a of FIG. 2A, forsake of brevity. However, this description applies equally to theembodiments of FIGS. 2B-H. The device 600 may define a cavity 620 forreceiving a distal portion of the heated aerosol-generating article 200a. A plurality of external heating elements 630 may be located in thecavity 620 and, when the article 200 a may be engaged within the cavity620, the heating elements 630 may surround the liquid retention medium210 a. The external heating elements 630 may be activated in order toheat the liquid retention medium 210 a by conduction. The externalheating elements 630 may be activated to also heat the liquid retentionmedium 210 a via radiation. The liquid aerosol-forming substrate 216 athat may be retained within the liquid retention medium 210 a may beheated and vaporized. As air is drawn through the article 200 a, thevaporized aerosol-forming substrate 216 a may be entrained in the air(shown by air flow path ‘A’), as the air is drawn into the coolingelement 220 a of the article 200 a. The vaporized aerosol-formingsubstrate 216 a may cool within the aerosol-cooling section 220 a andcondense to form a generated aerosol. The generated aerosol may then bedischarged from the vapor-generating article 200 a.

FIG. 6 illustrates the use of an aerosol-generating device 700 having aninternal heating element 730. The aerosol-generating device 700 mayinclude a solid aerosol-forming substrate 216 a (not explicitly depictedin FIG. 6, as the frangible capsule 212 a has already been ruptured, inthis configuration). The device 700 may define a cavity 720 that mayreceive a distal portion 250 a (FIG. 2A) of the heatedaerosol-generating article 200 a. A heating element 730, that may forexample be blade-shaped, may be located in the cavity 720 and, when thearticle 200 a may be engaged within the cavity 720 the heating element730 may extend into the lumen 214 a (FIG. 2A) of the liquid retentionmedium 210 a. The internal heating element 730 may be activated to heatthe liquid retention medium 210 a by radiation. The liquidaerosol-forming substrate 216 a may be retained within the liquidretention medium 210 a to be heated and vaporized. Air may be drawnthrough the article 200 a, such that the vaporized aerosol-formingsubstrate 216 a may be entrained in the air that may be drawn throughthe cooling element 220 a of the article 200 a. The vaporizedaerosol-forming substrate 216 a may cool within the aerosol-coolingsection 220 a and condense to form a generated aerosol. The generatedaerosol may be discharged from the article 200 a. While the device 700is shown interfacing with article 200 a, it should be understood thatthe device 700 may also interface with any of the articles 200 b-hdescribed above.

FIG. 7 illustrates a use of the heated aerosol-generating article 200 a.The aerosol-generating device 800 may be an aerosol-generating devicehaving an internal heating element 830 (which may be identical to theheating element 730 of FIG. 6). The aerosol-generating device 800 mayengage with a heat diffuser element 100 (FIG. 1), in addition to theaerosol-generating article 200 a. The heat diffuser element 100 may be asubstantially cylindrical element that may be formed from glass fibre.In an embodiment, the heat diffuser element 100 may be made from otherporous materials, such as ceramic fibres, ceramic foams, or sinteredmetals. The heat diffuser element 100 may define one or morelongitudinally extending slots 140 (FIG. 1) that may allow the heatdiffuser element 100 to be penetrated by the heating element 830 of theaerosol-generating device 800. The internal heating element 830 may beactivated to heat the heat diffuser element 100 by conduction. Theinternal heating element 830 may be activated to also heat the heatdiffuser element 100 by radiation. Air may be drawn through the device800 (see air flow ‘B’), and the air may pass through the heat diffuser100. The heated air may then be drawn into the aerosol-generatingarticle 200 a to pass through the liquid retention medium 210 a. Theliquid aerosol-forming substrate 216 a may be retained within the liquidretention medium 210 a (where the substrate 216 a is not shown in FIG.7, as the capsule 212 a has already been ruptured in thisconfiguration), and the substrate 216 a may be heated and vaporized bythis heated air. The air may be drawn through the article 200 a, so thatthe vaporized aerosol-forming substrate 216 a may be entrained in theair drawn through the cooling element 220 a of the article 200 a. Thevaporized aerosol-forming substrate 216 a may cool within theaerosol-cooling element 220 a and condense to form a generated aerosol.The generated aerosol may then be discharged from the article 200 a.While the device 800 is shown interfacing with article 200 a, it shouldbe understood that the device 800 may also interface with any of thearticles 200 b-h described above.

The specific embodiments and examples described above illustrate but donot limit the example embodiments. It is to be understood that otherembodiments may be made, and the specific embodiments and examplesdescribed herein are not exhaustive.

What is claimed is:
 1. An aerosol-generating article, comprising: aplurality of elements coaxially aligned and assembled within a wrapper,the article having an outlet end and a distal end upstream from theoutlet end; a liquid aerosol-forming substrate;and a liquid retentionmedium for retaining the liquid aerosol-forming substrate, wherein thewrapper is formed from a sheet of liquid-impervious material, the liquidretention medium being in a first element of the plurality of elements.2. The aerosol-generating article of claim 1, wherein the liquidaerosol-forming substrate is releasably contained within a frangiblecapsule, the frangible capsule being near the liquid retention mediumfor retaining the liquid aerosol-forming substrate within the articleafter its release from the frangible capsule.
 3. The aerosol-generatingarticle of claim 2, wherein the frangible capsule is in the liquidretention medium.
 4. The aerosol-generating article of claim 2, whereinthe liquid retention medium is in the form of a tube having a lumen, andthe frangible capsule is located within the lumen of the tube.
 5. Theaerosol-generating article of claim 1, wherein the liquid retentionmedium includes an absorbent polymeric material.
 6. Theaerosol-generating article of claim 2, wherein the frangible capsule isconfigured to rupture by application of an external force.
 7. Theaerosol-generating article of claim 2, wherein the frangible capsule isconfigured to be pierced by a piercing element.
 8. Theaerosol-generating article of claim 1, further comprising: a coolingsection located downstream from the liquid retention element, thecooling section being a second element of the plurality of elements. 9.The aerosol-generating article of claim 1, wherein the liquidaerosol-forming substrate includes between 10 weight percent and 25weight percent water, an aerosol former, and at least one flavorant. 10.The aerosol-generating article of claim 1, further comprising: amouthpiece filter located at the outlet end of the article, themouthpiece filter being a third element of the plurality of elements.11. The aerosol-generating article of claim 1, further comprising: aplug located at the distal end of the article, the article beingconfigured to draw air into the article at or adjacent to the distalend, through the article, and out of the outlet end of the article if anegative pressure is applied at the outlet end.
 12. Theaerosol-generating article of claim 1, wherein the wrapper is one of asheet of polymeric material, a sheet of treated paper, and a sheet ofmetallic foil.
 13. An aerosol-generating system, comprising: anaerosol-generating article, the aerosol-generating article including, aplurality of elements coaxially aligned and assembled within a wrapper,the article having an outlet end and a distal end upstream from theoutlet end, a liquid aerosol-forming substrate, and a liquid retentionmedium for retaining the liquid aerosol-forming substrate, the wrapperbeing formed from a sheet of liquid-impervious material, the liquidretention medium being in a first element of the plurality of elements;and an electrically-operated aerosol-generating device, theelectrically-operated aerosol-generating device including a heatingelement for heating the aerosol-forming substrate to form an aerosol.14. A method of using an aerosol-generating article, theaerosol-generating article including a plurality of elements coaxiallyaligned and assembled within a wrapper, the article having an outlet endand a distal end upstream from the outlet end, a liquid aerosol-formingsubstrate, and a liquid retention medium for retaining the liquidaerosol-forming substrate, the wrapper being formed from a sheet ofliquid-impervious material, the liquid retention medium being in a firstelement of the plurality of elements, the method comprising: couplingthe aerosol-generating article to an electrically-operatedaerosol-generating device; activating a heating element of theelectrically-operated aerosol-generating device; and drawing air throughthe aerosol-generating article, the liquid aerosol-forming substratebeing vaporized by heat energy supplied by the heating element andcondensed to form an aerosol entrained in the air.
 15. The method ofclaim 14, wherein the liquid aerosol-forming substrate is containedwithin a frangible capsule, the method further including the step of,releasing the liquid aerosol-forming substrate from the frangiblecapsule such that it is retained within the article by the liquidretention medium.